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: volcanic ash in the atmosphere decreases the temperature by blocking the sun, Fact2: Ash clouds are a particular problem for aircraft., Question: What are particular problems for aircraft in the atmosphere? (A) transportation (B) clog airways (C) extremely low humidity (D) volcanic clouds (E) feedback mechanisms (F) negative feedback (G) gas spreads in the air (H) very complex
[EX A]: D

[EX Q]: Fact1: Cell division is how organisms grow and repair themselves., Fact2: Cell division is by mitosis ., Question: What is required by division? (A) voltage (B) Microscope (C) loose soil (D) Energy. (E) Energy (F) relocation (G) warmth (H) mitosis
[EX A]: H

[EX Q]: Fact1: Veins generally carry deoxygenated blood., Fact2: Blood returns to the heart by the veins., Question: what supplies the heart? (A) organ (B) Energy (C) veins (D) ovaries (E) glucose (F) oxygen (G) sugar (H) alveoli
[EX A]:
C