Question: About the Texas county that has the official website http://www.co.mclennan.tx.us,  tell me its inception time.
Choices:
1966-12-19
1850
1924-08-07
1963
-660
1839-02-15
1782-04-21
870
1976-01-01
1861-03-17
Program:
function: FindAll
function: FilterStr
dependencies: 0
inputs: official website
http://www.co.mclennan.tx.us
function: FilterConcept
dependencies: 1
inputs: county of Texas
function: QueryAttr
dependencies: 2
inputs: inception
SPARQL: SELECT DISTINCT ?pv WHERE { ?e <pred:instance_of> ?c . ?c <pred:name> "county of Texas" . ?e <official_website> ?pv_1 . ?pv_1 <pred:value> "http://www.co.mclennan.tx.us" . ?e <inception> ?pv .  }
Answer: 1850