The equation E t = 5 1.8 t gives the estimated number of employees at a

Choice A is correct. For an exponential function of the form $E\left(t\right)=a{\left(b\right)}^t$, where $a$ and $b$ are constants, the initial value of the function—that is, the value of the function when $t=0$—is $a$ and the value of the function increases by a factor of $b$ each time $t$ increases by $1$. Since the function $E\left(t\right)=5{\left(1.8\right)}^t$ gives the estimated number of employees at a restaurant and $t$ is the number of years since the restaurant opened, the best interpretation of the number $5$ in this context is the estimated number of employees when $t=0$, or when the restaurant opened.

Choice B is incorrect and may result from conceptual errors.

Choice C is incorrect and may result from conceptual errors.

Choice D is incorrect and may result from conceptual errors.