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: Mutations are essential for evolution to occur., Fact2: Evolution Change through time., Question: What is needed for changes to occur? (A) exercise (B) mutations (C) growth (D) healthy animals (E) environment (F) evaporation (G) Exfoliation (H) births
A:
B