The ozone layer serves and protects us from harmful uv radiation that comes from the.
a. point-source pollutant
b. thermal pollutant
c. sunscreen
d. blanket

is this a psat question, if so do not cheat try your best.

well, i believe that the answer is 2. : 3

the answer is c.

by: nicholas dooley

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.