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: 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
D

Fact1: astronauts require preserved food for extended flights, Fact2: Most of the Shuttle foods are preserved by dehydration, which saves weight and storage space., Question: astronauts require what food for extended flights? (A) Echinoderm. (B) layers of fat (C) dehydrated (D) fresh (E) hand picked (F) nutrients (G) frozen (H) hydration
C

Fact1: sand dunes are formed by the wind transporting and depositing sand, Fact2: Desert Dunes Desert sand dunes occur in an amazing diversity of forms., Question: deserts are a location where wind transport can deposit what (A) plant (B) rocks (C) crust (D) grains (E) money (F) sand (G) matter (H) soils

F