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").

[EX Q]: Fact1: acid rain has a negative impact on water quality, Fact2: Sulfur dioxide causes acid rain., Question: What has a negative impact on water quality? (A) Reverse osmosis (B) fossil fuels (C) Fresh water (D) Carbon filter (E) chlorofluorocarbons (F) Sulfur dioxide (G) Pollution (H) harmful substances
[EX A]: F

[EX Q]: Fact1: wind and rain cause erosion, Fact2: Water, in the form of rain, is the most effective agent of erosion., Question: What causes erosion the most? (A) streams (B) motion (C) LEDs (D) water (E) Roads (F) rivers (G) Winter (H) wind
[EX A]: D

[EX Q]: Fact1: damming a river can cause a lake to form, Fact2: You can also water ski on Lake Mohave north of Davis Dam., Question: To open more areas for water skiing, engineers could (A) dam more rivers (B) to move people (C) protect them (D) vacation in Norway (E) Move to another area (F) build more snow machines (G) scrap all steam locomotives (H) Electric generators
[EX A]:
A