user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: which class of locomotives are built by neilson and company? 
Knowledge Triplets: Neilson and Company, rail.locomotive_class.built_by, G&SWR 141 Class
SECR C class, rail.locomotive_class.built_by, Sharp, Stewart and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, Midland Railway 700 Class
Caledonian Railway 264 Class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, SECR C class
G&SWR 141 Class, rail.locomotive_class.built_by, Neilson and Company
Avonside Engine Company, rail.locomotive_builder.locomotive_classes_built, NZR J class
GCR Class 8, rail.locomotive_class.built_by, Beyer, Peacock and Company
Neilson and Company, rail.locomotive_class.built_by, LB&SCR D1 class
Queensland B12 class locomotive, rail.locomotive_class.gauge_mm, 1066.8
Neilson and Company, rail.locomotive_class.built_by, South African Class 6B 4-6-0
Midland Railway 700 Class, rail.locomotive_class.uic_classification, C n2
NZR C class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, Caledonian Railway 264 Class
LSWR 460 class, rail.locomotive_class.length, 15.82
Sharp, Stewart and Company, rail.locomotive_builder.locomotive_classes_built, Caledonian Railway 812 and 652 Classes
LSWR 415 class, rail.locomotive_class.built_by, Dübs and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, CGR 1st Class 4-4-0 1879
Midland Railway 700 Class, rail.locomotive_class.built_by, Dübs and Company
NBR D class 0-6-0T, rail.locomotive_class.built_by, Sharp, Stewart and Company
NZR C class, rail.locomotive_class.built_by, Dübs and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, NZR C class
Caledonian Railway 812 and 652 Classes, rail.locomotive_class.built_by, Dübs and Company
Neilson and Company, rail.locomotive_class.built_by, CGR 4th Class 4-6-0TT 1882
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LSWR 415 class
NZR J class, rail.locomotive_class.built_by, Avonside Engine Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, Metropolitan Railway C Class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, South African Class 6B 4-6-0
GCR Class 9J, rail.locomotive_class.built_by, Beyer, Peacock and Company
CGR 1st Class 4-4-0TT 1881, rail.locomotive_class.introduced, 1881
GNRI Class Q, rail.locomotive_class.built_by, Beyer, Peacock and Company
Neilson and Company, rail.locomotive_class.built_by, CGR 1st Class 4-4-0 1879
Sharp, Stewart and Company, rail.locomotive_builder.locomotive_classes_built, SECR C class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, GCR Class 8
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, G&SWR 141 Class
Beyer, Peacock and Company, rail.locomotive_builder.locomotive_classes_built, GNRI Class Q
NZR C class, rail.locomotive_class.gauge_mm, 1066.8
South African Class 6B 4-6-0, rail.locomotive_class.built_by, Neilson and Company
NZR J class, rail.locomotive_class.gauge_mm, 1066.8
GCR Class 8, rail.locomotive_class.built_by, Neilson and Company
CGR 3rd Class 4-4-0 1884, rail.locomotive_class.built_by, Neilson and Company
North British Locomotive Company, rail.locomotive_builder.locomotive_classes_built, New South Wales D50 class locomotive
Queensland A10 Neilson class locomotive, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, GCR Class 9J
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, CGR 4th Class 4-6-0TT 1882
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, SECR B1 class
Metropolitan Railway C Class, rail.locomotive_class.uic_classification, B2′ n2t
South African Class 6C 4-6-0, rail.locomotive_class.built_by, Neilson and Company
NBR C Class, rail.locomotive_class.built_by, Sharp, Stewart and Company
SECR C class, rail.locomotive_class.uic_classification, C n2
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, Queensland B12 class locomotive
LCDR M class, rail.locomotive_class.built_by, Neilson and Company
CGR 4th Class 4-6-0TT 1882, rail.locomotive_class.built_by, Neilson and Company
NZR J class, rail.locomotive_class.built_by, Dübs and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, NZR D class
Neilson and Company, rail.locomotive_class.built_by, LSWR 415 class
NBR C Class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, New South Wales D50 class locomotive
G&SWR 9 Class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_class.built_by, Caledonian Railway 264 Class
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, LSWR 415 class
LNER Class D40, rail.locomotive_class.built_by, North British Locomotive Company
Sharp, Stewart and Company, rail.locomotive_builder.locomotive_classes_built, NBR C Class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, CGR 3rd Class 4-4-0 1884
Avonside Engine Company, rail.locomotive_builder.locomotive_classes_built, Queensland B12 class locomotive
m.0k29rqh, dataworld.gardening_hint.last_referenced_by, Caledonian Railway 812 and 652 Classes
CGR 1st Class 4-4-0 1879, rail.locomotive_class.built_by, Neilson and Company
NZR D class, rail.locomotive_class.built_by, Dübs and Company
Queensland B12 class locomotive, rail.locomotive_class.built_by, Dübs and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, South African Class 6C 4-6-0
Yorkshire Engine Company, rail.locomotive_builder.locomotive_classes_built, GCR Class 9J
Queensland B12 class locomotive, rail.locomotive_class.built_by, Neilson and Company
SECR B1 class, rail.locomotive_class.built_by, Neilson and Company
GNRI Class Q, rail.locomotive_class.built_by, Neilson and Company
CGR 3rd Class 4-4-0 1884, rail.locomotive_class.introduced, 1884
New South Wales D50 class locomotive, rail.locomotive_class.built_by, North British Locomotive Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, Queensland B12 class locomotive
GCR Class 9A, rail.locomotive_class.built_by, Neilson and Company
SECR C class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_class.built_by, Queensland B12 class locomotive
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, South African Class 6C 4-6-0
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LNER class D41
New South Wales D50 class locomotive, rail.locomotive_class.built_by, Beyer, Peacock and Company
GNRI Class Q, rail.locomotive_class.built_by, North British Locomotive Company
South African Class 6C 4-6-0, rail.locomotive_class.length, 15.729
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, NZR D class
m.0j39d82, dataworld.gardening_hint.last_referenced_by, Caledonian Railway 264 Class
LSWR 415 class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LCDR M class
LSWR 415 class, rail.locomotive_class.built_by, Beyer, Peacock and Company
G&SWR 187 Class, rail.locomotive_class.built_by, Neilson and Company
South African Class 6B 4-6-0, rail.locomotive_class.built_by, Dübs and Company
GCR Class 9J, rail.locomotive_class.built_by, Neilson and Company
Beyer, Peacock and Company, rail.locomotive_builder.locomotive_classes_built, New South Wales D50 class locomotive
NZR D class, rail.locomotive_class.built_by, Neilson and Company
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, New South Wales D50 class locomotive
Neilson and Company, rail.locomotive_class.built_by, G&SWR 95 Class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, G&SWR 187 Class
New South Wales D50 class locomotive, rail.locomotive_class.built_by, Neilson and Company
CGR 1st Class 4-4-0 1879, rail.locomotive_class.built_by, Avonside Engine Company
Queensland B12 class locomotive, rail.locomotive_class.built_by, Avonside Engine Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, GCR Class 9A
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, Queensland A10 Neilson class locomotive
LNER Class D40, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LB&SCR D1 class
LNER class D41, rail.locomotive_class.built_by, Neilson and Company
Metropolitan Railway C Class, rail.locomotive_class.built_by, Neilson and Company
Beyer, Peacock and Company, rail.locomotive_builder.locomotive_classes_built, GCR Class 8
Avonside Engine Company, rail.locomotive_builder.locomotive_classes_built, CGR 1st Class 4-4-0 1879
CGR 1st Class 4-4-0TT 1881, rail.locomotive_class.built_by, Neilson and Company
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, Caledonian Railway 812 and 652 Classes
Caledonian Railway 812 and 652 Classes, rail.locomotive_class.built_by, Sharp, Stewart and Company
GCR Class 9J, rail.locomotive_class.built_by, Yorkshire Engine Company
G&SWR 95 Class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LNER Class D40
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, NBR C Class
Neilson and Company, rail.locomotive_class.built_by, LNER class D41
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, GNRI Class Q
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, NZR C class
m.0tjt4qd, dataworld.gardening_hint.last_referenced_by, Queensland A10 Neilson class locomotive
Beyer, Peacock and Company, rail.locomotive_builder.locomotive_classes_built, LSWR 415 class
GNRI Class Q, rail.locomotive_class.gauge_mm, 1600.2
Neilson and Company, rail.locomotive_class.built_by, Queensland A10 Neilson class locomotive
North British Locomotive Company, rail.locomotive_builder.locomotive_classes_built, LNER Class D40
LB&SCR D1 class, rail.locomotive_class.built_by, Neilson and Company
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, South African Class 6B 4-6-0
Neilson and Company, rail.locomotive_class.built_by, LCDR M class
Queensland A10 Neilson class locomotive, rail.locomotive_class.gauge_mm, 1066.8
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, CGR 1st Class 4-4-0TT 1881
Neilson and Company, rail.locomotive_class.built_by, SECR C class
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, NZR J class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LSWR 460 class
Sharp, Stewart and Company, rail.locomotive_builder.locomotive_classes_built, South African Class 6C 4-6-0
LSWR 460 class, rail.locomotive_class.built_by, Neilson and Company
SECR B1 class, rail.locomotive_class.uic_classification, 2′B
G&SWR 58 Class, rail.locomotive_class.built_by, Neilson and Company
Dübs and Company, rail.locomotive_builder.locomotive_classes_built, Midland Railway 700 Class
GCR Class 9J, rail.locomotive_class.uic_classification, C n2t
Neilson and Company, rail.locomotive_class.built_by, Metropolitan Railway C Class
Neilson and Company, rail.locomotive_class.built_by, SECR B1 class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, G&SWR 58 Class
Neilson and Company, rail.locomotive_class.built_by, LSWR 460 class
G&SWR 187 Class, rail.locomotive_class.length, 15.42
GCR Class 8, rail.locomotive_class.uic_classification, 2′C
NZR D class, rail.locomotive_class.gauge_mm, 1066.8
New South Wales D50 class locomotive, rail.locomotive_class.built_by, Dübs and Company
South African Class 6C 4-6-0, rail.locomotive_class.built_by, Dübs and Company
NZR J class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, LSWR A12 class
Neilson and Company, rail.locomotive_class.built_by, LSWR A12 class
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, G&SWR 9 Class
CGR 1st Class 4-4-0 1879, rail.locomotive_class.introduced, 1879
LCDR M class, rail.locomotive_class.uic_classification, 2′B n2
Sharp, Stewart and Company, rail.locomotive_builder.locomotive_classes_built, NBR D class 0-6-0T
Beyer, Peacock and Company, rail.locomotive_builder.locomotive_classes_built, GCR Class 9J
LSWR 460 class, rail.locomotive_class.uic_classification, 2'Bn
Caledonian Railway 812 and 652 Classes, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, Caledonian Railway 812 and 652 Classes
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, G&SWR 95 Class
Neilson and Company, rail.locomotive_class.built_by, GNRI Class Q
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, NZR J class
LSWR A12 class, rail.locomotive_class.built_by, Neilson and Company
South African Class 6C 4-6-0, rail.locomotive_class.built_by, Sharp, Stewart and Company
Caledonian Railway 812 and 652 Classes, rail.locomotive_class.uic_classification, Cn
GCR Class 9J, rail.locomotive_class.length, 16.18
Midland Railway 700 Class, rail.locomotive_class.built_by, Neilson and Company
Neilson and Company, rail.locomotive_builder.locomotive_classes_built, NBR D class 0-6-0T
North British Locomotive Company, rail.locomotive_builder.locomotive_classes_built, GNRI Class Q
NBR D class 0-6-0T, rail.locomotive_class.built_by, Neilson and Company
South African Class 6C 4-6-0, rail.locomotive_class.introduced, 1896

Answer: CGR 4th Class 4-6-0TT 1882
NBR C Class
NBR D class 0-6-0T
G&SWR 187 Class
GCR Class 8
CGR 3rd Class 4-4-0 1884
LNER Class D40
Queensland A10 Neilson class locomotive
G&SWR 141 Class
LNER class D41
GCR Class 9J
G&SWR 95 Class
G&SWR 9 Class
G&SWR 58 Class
SECR B1 class
Midland Railway 700 Class
Metropolitan Railway C Class
CGR 1st Class 4-4-0 1879
GNRI Class Q
LB&SCR D1 class
NZR C class
LSWR 460 class
Caledonian Railway 812 and 652 Classes
South African Class 6C 4-6-0
Caledonian Railway 264 Class
NZR D class
South African Class 6B 4-6-0
GCR Class 9A
LCDR M class
LSWR 415 class
SECR C class
NZR J class
New South Wales D50 class locomotive
CGR 1st Class 4-4-0TT 1881
LSWR A12 class
Queensland B12 class locomotive