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: insulated material can be used for keeping warm, Fact2: Sunlight heats the ground, warming it up., Question: How can heat be kept? (A) an electric stove (B) exposed material (C) insulated material (D) hydration (E) permeable material (F) electricity (G) wet material (H) In the winter
C