The use of an electron microscope would most benefit the study of

I do not know what the options are, but you should choose something really small. Electron microscopes use a different technology than light microscopes. They use electron beams which gives them a higher resolution and magnification.

These might be some options:

Microorganisms (general)

Cells / cell interior

Hope it helped,

BioTeacher101

(If you have any questions feel free to ask them in the comments)

rising temperatures because when water vapor in the air is cooled, it condenses. it turns back into a liquid and attaches to dust particles in the air. these very small water droplets group together to form clouds