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: clouds are formed by water vapor rising into colder regions of the atmosphere and condensing, Fact2: This water evaporates into water vapor and rises up into the atmosphere., Question: what process must occur to form clouds? (A) thunderstorms (B) Movement of an air mass (C) evaporation (D) nimbus (E) snow (F) water evaporating (G) chemical changes (H) cloudy and rainy weather
Output:
F