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").

[EX Q]: Fact1: Some viruses can cause cancer., Fact2: Cancer is an example of a mutation in cells., Question: What can mutate cells? (A) Allergies (B) water (C) fruits (D) flow of electrons (E) vegetables (F) harmful substances (G) rays or beams (H) some viruses
[EX A]: H

[EX Q]: 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
[EX A]: B

[EX Q]: Fact1: Cells are the microscopic building blocks of organisms., Fact2: Fish Fish are the ultimate aquatic organism., Question: Cells are the microscopic building blocks of what? (A) viruses (B) plants (C) fish (D) the Moon (E) the Sun (F) Man (G) live (H) life
[EX A]:
C