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: carbon dioxide concentrations in the air have increased over the last decade dramatically, Fact2: Increases in carbon dioxide make the greenhouse effect worse., Question: How has the greenhouse effect changed in the last decade? (A) moved to South America (B) improved (C) Temperature (D) fossil fuels (E) has become cooler (F) worsened (G) climate (H) growth
Output:
F