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: dew is formed when water vapor condenses over night, Fact2: If the cooling is sufficient, water vapor condenses into clouds., Question: Dew is formed when _ occurs over night (A) cooling (B) imbalanced (C) rain (D) storms (E) warm (F) boiling (G) a solute (H) Joules
A