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: Cells secrete acids and bases to maintain the proper pH for enzymes to work., Fact2: Phosphatases are enzymes that remove phosphates from other enzymes., Question: What is needed from cells for phosphatases to keep the proper pH? (A) plasma (B) secretion of bases only (C) secretion of proteins (D) metabolic reaction (E) it helps plants in growing (F) Positive charges (G) Transfers energy (H) secretion of acids and bases
H