Given the task definition and input, reply with output. 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").

Fact1: cutting down trees has a negative impact on an ecosystem, Fact2: Oak trees are so strong., Question: What has a negative impact on an ecosystem? (A) massive damage (B) Pesticides (C) good weather (D) Destroy bridges (E) planting trees (F) normal water levels (G) deforestation (H) cutting down oaks
H