You will be given a definition of a task first, then some input of the task.
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: a switch is used to start the flow of current in an electrical circuit, Fact2: An electrical current is the flow of electric charge., Question: A switch is used to start the what of electric charge in an electrical circuit? (A) emptying (B) O3 (C) copper (D) flow (E) motion (F) stasis (G) deletion (H) energy
Output:
D