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: Plasma cells are activated B cells that secrete antibodies., Fact2: Antibodies are produced by plasma cells., Question: antibodies are produced by activated B cells that do what? (A) Animal survival (B) killing insects (C) interact (D) secrete them (E) migrate (F) reproduce (G) competition (H) Allergies
D

Fact1: when a metal rusts , that metal becomes orange on the surface, Fact2: Iron rusts in the presence of oxygen and water., Question: Exposure to oxygen and water can cause iron to (A) decrease strength (B) melt (C) uncontrollable burning (D) thermal expansion (E) turn orange on the surface (F) vibrate (G) Extremes of temperature (H) levitate
E

Fact1: Prokaryotes are single-celled organisms that lack a nucleus., Fact2: Prokaryotes All bacteria are prokaryotes., Question: What are single-celled organisms that lack a nucleus? (A) barnacles (B) bacteria (C) Most plants (D) ferns (E) orchids (F) cacti (G) PDAs (H) Leeuwenhoek
B