P t = 1,800 1.02 t The function P gives the estimated number of marine mammals

Choice B is correct. The function $P$ gives the estimated number of marine mammals in a certain area, where $t$ is the number of years since a study began. Since the value of $P\left(0\right)$ is the value of $P\left(t\right)$ when $t=0$, it follows that $P\left(0\right)=\mathrm{1,800}$ means that the value of $P\left(t\right)$ is $\mathrm{1,800}$ when $t=0$. Since $t$ is the number of years since the study began, it follows that $t=0$ is $0$ years since the study began, or when the study began. Therefore, the best interpretation of $P\left(0\right)=\mathrm{1,800}$ in this context is the estimated number of marine mammals in the area was $\mathrm{1,800}$ when the study began.

Choice A is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.

Choice D is incorrect and may result from conceptual or calculation errors.