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: a prism is used for refracting light, Fact2: Refraction is the bending of light cause by a speed change when it passes through different media., Question: What aspect of light changes when it passes from air into a prism? (A) power (B) seasons (C) speed (D) energy (E) a wave (F) Joules (G) heat (H) unique
[A]: C


[Q]: Fact1: Echinoderms lack a centralized nervous system., Fact2: Sand dollars and sea biscuits are also echinoderms., Question: What lacks a centralized nervous system? (A) Damaged hearing (B) Humans (C) Horses (D) Sand dollars (E) insects (F) Chickens (G) Pesticides (H) barnacles
[A]: D


[Q]: Fact1: Active immunity results when an immune response to a pathogen produces memory cells., Fact2: Pathogens are simply a variety of diseases which kill insects., Question: What prevents insects from being killed? (A) Fly swatter (B) Active immunity (C) Exfoliation (D) a cuticle (E) food (F) bugs (G) rays or beams (H) resistance
[A]:
B