Question

informative introduction? turbulence is a normal part of air travel and is not usually dangerous. which background information should be added? helicopters can go up and down straight from the ground. cockpits are the front parts of planes where the pilots sit. imagine riding a roller coaster in the sky - thats what turbulence can feel like on an airplane.

Explanation:

The question is about adding background info related to turbulence in air travel. The first option is about helicopters, irrelevant. The second is about cockpits, not related. The third option explains what turbulence feels like (comparing to a roller coaster in the sky), which provides relevant background to the statement about turbulence in air travel.

Answer:

The correct option is: "Imagine riding a roller coaster in the sky - that's what turbulence can feel like on an airplane."