Given the task definition and input, reply with output. 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: Amphibians have a relatively complex circulatory system with a three-chambered heart., Fact2: Blood is pumped around the body by a heart ., Question: What do amphibians pump around the body in a complex manner? (A) SO2 (B) food (C) Energy. (D) oxygen (E) Energy (F) thoughts (G) blood (H) water
G