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").

[EX Q]: Fact1: Flowing water can slowly dissolve carbon in sedimentary rock., Fact2: Rivers and streams are bodies of fresh, flowing water., Question: What can slowly dissolve carbon in sedimentary rock? (A) hydrocarbons (B) acetic acid (C) precipitation (D) evaporation (E) rivers and streams (F) puddles (G) ponds (H) nitrogen
[EX A]: E

[EX Q]: Fact1: Evolution occurs in response to a change in the environment., Fact2: Extinction is a natural part or the process of evolution., Question: What happens to an environment to cause extinction?  (A) relocation (B) changes (C) rain (D) exposure (E) forces (F) wind (G) Pollution (H) discovery
[EX A]: B

[EX Q]: Fact1: fog is formed by water vapor condensing in the air, Fact2: Fog is essentially very low clouds, consisting of water vapor cooling and beginning to condense., Question: What happens when water vapors cool down? (A) colder weather (B) Fog is formed (C) Heat energy (D) evaporation (E) chemical changes (F) Something to move (G) prolactin release (H) Energy.
[EX A]:
B