Q: 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: Cells secrete acids and bases to maintain the proper pH for enzymes to work., Fact2: Most human enzymes work at a optimal pH of 7.4, but other enzymes work at many different pH ranges., Question: Cells secrete acids and bases to maintain what? (A) Chemical energy (B) resistance (C) increases a body's strength (D) To keep their body heat. (E) most human enzymes (F) aerobic capacity (G) allow growth (H) temperature
A:
E