Why are units of measurement useful?
a) to complete the sl system
b) to make comparing amounts easier
c) to allow scientists to do experiments
d) to design better tools such as stopwatches

B

Explanation:

If you are comparing an amount you are trying to find the quantity or the total of something or the size  therefore answer B is the right answer  

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation: