How is a cloud produced?

1. Warm air collides with cold air.
2. Tiny water droplets condense around different types of particles in the air.
3. The troposphere touches the ground.
4. A high-altitude aircraft gives off hot exhaust.

Select the correct answer.

A. If the text is expository, read it quickly; if it is narrative, read it carefully. If the question is about a detail, find the detail. If it's general, infer the answer.
B. If the text is expository, read it quickly; if it is narrative, read it carefully. Find the detail you need and infer the answer. If it doesn't sound right, find another detail.
C. If the text is expository, read it carefully; if it is narrative, read it quickly. Then infer the answer. If the answer doesn't make sense, find a detail.