Detailed Instructions: 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").
Q: Fact1: Vertebrate chordates have a backbone., Fact2: Because reptiles are vertebrates, they are chordates., Question: What has a backbone? (A) reptiles (B) four limbs (C) humans (D) the Sun (E) bacteria (F) insects (G) sponges (H) elephants
A:
A