You will be given a definition of a task first, then some input of the task.
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: coal is used for generating heat by burning, Fact2: Coal and lignite are the lithified remains of plants., Question: What are the lithified remains of plants used for? (A) heat production (B) generating heat by burning (C) harvesting crops (D) damming rivers (E) food and shelter (F) heat is produced (G) A transportation fuel (H) planting seeds
Output:
B