The initial size of a population is 2100 and it has an instantaneous decay rate of -18% per year. Which one of the following exponential functions model this population where t is measured in years?

a. P(t) = 2100(0.82)ᵗ
b. P(t) = 2100e⁰'⁸²ᵗ
c. P(t) = 2100e⁰'¹⁸ᵗ
d. P(t) = 2100(0.18)ᵗ