What kind of wave is a sound wave? A. an electromagnetic wave
B. a heat wave
C. a mechanical wave
D. an energy wave

It's C

Explanation:

Mechanical vibrations of sound conductance qualify sound waves as mechanical waves. ( I hope that made sense but I know it's C. If ot's wrong please tell me)

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..

that would be because of both gravity and friction. so     c