Solve the Problem $S(t)=S_{0} e^{-a t}$ , Where $t$ Is Time in Years

Multiple Choice

Solve the problem.
-The sales of a mature product (one which has passed its peak) will decline by the function $S(t) =S_{0} e^{-a t}$ , where $t$ is time in years. Find the sales after 9 years if $a=0.14$ and $S_{0}=56,100$ .

A) 7957
B) 227,497
C) 15,913
D) 64,530