Why do the cells in all living things need energy?
a. to fuel their chemical reactions
b. to them decompose
c. to communicate with other cells
d. so they can block sunlight

a. to fuel their chemical reactions

Explanation:

Cells aren't meant to decompose things, there's no reason for them to communicate with other cells, and cells blocking sunlight just doesn't make much sense.

I hope this helps! :D

newton's first law of motion

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.