Detailed Instructions: In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Problem:[header] How to clean ivory [title] Dust ivory using a paintbrush. [step] Start off cleaning your ivory by brushing with a paintbrush, which is the most delicate method. Be sure to use a soft, clean paintbrush, and to work in one direction so that you don't spread dirt or impurities around the surface of the object. <sep> (A) [substeps] For a stubborn mess, spread powdered sugar on a cotton rag. [title] After dusting and swiping down the ivory, buff the item, about 2-3 times. (B) [substeps] Make sure that you brush in the direction of the grain. Oil that you use on ivory creates thin cracks, and dirt will quickly accumulate on the surface, which can make the surface more dirty and lead to more blemishes. (C) [substeps] Before handling ivory, wear clean, white cloth gloves. Without gloves, the oil from your fingers can transfer to the ivory and affect its coloring. (D) [substeps] A medium to high-grit hand duster is always the most effective from here. Start at the lower end of the ivory, focusing on the thinnest point of the object.
Solution:
C