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").
Input: Fact1: planting trees has a positive impact on an ecosystem, Fact2: Birds are important components of ecosystems., Question: What has a positive impact on birds (A) exercise (B) planting trees (C) recycling (D) community policing (E) food and shelter (F) with their fur (G) squirrels (H) four limbs
Output:
B