Detailed Instructions: 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").
Q: Fact1: Amphibians have a relatively complex circulatory system with a three-chambered heart., Fact2: Frogs, toads and salamanders are amphibians., Question: What sort of circulatory system do frogs, toads, and salamanders share? (A) live birth (B) It helps them survive (C) matter vibrating (D) two-chambered heart (E) Veins and arteries. (F) biological diversity (G) three-chambered heart (H) four-chambered heart
A:
G