Given the task definition, example input & output, solve the new input case.
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").
Example: Fact1: a plant requires sunlight to grow, Fact2: Plants to avoid are fast-growing vines that can take over an area in no time., Question: What requires sunlight in order to take over an area? (A) spores (B) fish (C) plants (D) humans (E) pods (F) Oak (G) opossums (H) coral
Output: C
This is a good example. Based on the facts plants require sunlight in order to take over an area.

New input case for you: Fact1: Plasma cells are activated B cells that secrete antibodies., Fact2: Antibodies are produced to fight antigens., Question: what do plasma cells secrete? (A) Chemical energy (B) h2o (C) oxygen (D) antigen fighters (E) harmful substances (F) bioaerosols (G) mucus (H) Organic compounds
Output:
D