Q: 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: astronauts require preserved food for extended flights, Fact2: Freeze-drying Freeze drying is a method of preserving materials., Question: Which of the following keeps food viable for extended flights? (A) evaporation (B) microwaving (C) boiling (D) freeze drying (E) layers of fat (F) deep frying (G) mechanical (H) Dehydration
A:
D