Detailed Instructions: 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").
Problem:Fact1: Constriction occurs when the muscular walls of blood vessels contract., Fact2: Dehydration causes vessels to constrict and blood to thicken., Question: What causes blood to thicken? (A) Constriction (B) evaporation (C) heat or cold (D) thirst (E) permineralization (F) sweating (G) flow of electrons (H) matter vibrating
Solution:
A