An environmental study of a certain suburban community suggests that t years from now, the average level of carbon monoxide in the air will be Q(t) = 4e^0.03t parts per million.

a. At what rate will the carbon monoxide level be changing with respect to time 2 years from now?

b. At what percentage rate will the carbon monoxide level be changing with respect to time t years from now? Does this percentage rate of change depend on t or is it constant?