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: Biomass is the total mass of organisms at a trophic level., Fact2: Each stage is a trophic level., Question: The total mass of organisms in an environmental stage is called what? (A) food pyramid (B) extinction (C) ecological pyramid (D) food chain (E) vegetation (F) food (G) ligt (H) biomass

A: H
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Q: Fact1: an egg requires warmth to survive, Fact2: First the frog lays the eggs, then the warmth from the sun makes the eggs hatch into baby tadpoles., Question: what keeps eggs warm? (A) ice (B) hair (C) wool (D) bears (E) fur (F) sun (G) moss (H) sand

A: F
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Q: Fact1: HIV infects and destroys helper T cells., Fact2: Because HIV attacks T cells, it essentially paralyzes the immune system., Question: what system does HIV attack? (A) complex (B) humans (C) infection (D) organ (E) brain (F) animals (G) spinal (H) immune

A:
H
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