What is accerleration

See explanation

Explanation:

Acceleration is defined as the change in velocity. In other words, if your velocity changes, then you are accelerating. And since velocity is a vector of both speed and direction, you don't have to be speeding up to be accelerating, you could also just be turning. Hope this helps!

e) none of the above answers are correct

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )