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: breathing is when a gill converts from oxygen in water into oxygen in blood, Fact2: Gill slits form gills in fish., Question: What converts oxygen in water into oxygen in blood? (A) sharks (B) germs (C) Enzymes (D) starfish (E) rivers (F) Jellyfish (G) streams (H) a fish
A:
H