Suppose that the population of a country can be modeled by the exponential equation P(t) = 3.6e^0.078t where P(t) gives the population in millions, and t represents time in years since a population study began. Find the rate at which this country's population is growing (given in millions of people per year) when t = 5.

a) 0.190
b) 0.115
c) 41.674
d) 0.415
e) 5.317
f) None of the above