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: 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
D

Fact1: erosion causes a river to become deeper and wider, Fact2: Weathering and erosion continue to shape it today., Question: Weathering causes what to become deeper and wider? (A) a landslide (B) Sediment (C) a mountain (D) a volcano (E) soils (F) rock (G) flooding (H) a river
H

Fact1: Mutations that lead to cancer usually occur in genes that control the cell cycle., Fact2: Cancer is an example of a mutation in cells., Question: What usually occur in genes that control the cell cycle? (A) Leptospirosis (B) competition (C) A Greek letter (D) a mutation in cells (E) Plant reproduction (F) biological diversity (G) resistance (H) resistance activities
D