An environmental study of a certain suburban community suggests that the average daily level of carbon monoxide in the air will be c(p) = 0.4p + 1 parts per million when the population is p thousand. It is estimated that t years from now the population of the community will be p(t) = 8 + 0.2t² thousand.

a. Express the level of carbon monoxide in the air as a function of time.

b. What will the carbon monoxide level be 2 years from now?

c. When will the carbon monoxide level reach 6.2 parts per million?