Teacher:In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").
Teacher: Now, understand the problem? Solve this instance: Fact1: Hair is a fiber that is found only in mammals., Fact2: Hair is largely made of keratin, a protein that contains a lot of the amino acid cystine ., Question: What do mammals contain? (A) food (B) ghosts (C) keratin (D) Animal fur (E) magic (F) soul (G) alveoli (H) four limbs
Student:
C