Given the task definition and input, reply with output. 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 solution is formed by one substance being dissolved in another substance, Fact2: White vinegar is a 5 percent acetic acid solution., Question: What is formed by one substance being dissolved in another substance? (A) patch reefs (B) hydrogen and oxygen (C) organic molecules (D) a hydraulic system (E) calcite (F) white vinegar (G) Calcium carbonate (H) salinity
F