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").

[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
[A]: D


[Q]: Fact1: natural disasters can cause animals to leave an environment, Fact2: And like fire, flooding is a common and widespread natural disaster., Question: What can cause animals to leave their environment? (A) predators (B) rainfall (C) space travel (D) flooding (E) drought (F) mines (G) wind (H) weather
[A]: D


[Q]: Fact1: Echinoderms use pheromones to communicate with each other., Fact2: All echinoderms are deuterostomes ., Question: What use pheromones to communicate with each other? (A) passenger pigeons (B) honeybees (C) deuterostomes (D) Most plants (E) insects (F) animals (G) huddle together (H) orchids
[A]:
C