Figuresk8r89 is banning me so heres free points also this is for a grade plz answer right

Hello i am going to be you today with your problems today. i believe that the answer is going to be. i hope this you have a great day.a. people around the world 

Airplanes usually fly in the lower part of the stratosphere - there is nearly no water vapor and it's very dry, so it to avoid big turbulences. it's about 8-10 kilometers above ground (depending on weather conditions, region etc.)