The Table Below Shows the Relationship Between the Number of Times

The table below shows the relationship between the number of times you get your car washed each month and your total monthly benefit from car washes. Each car wash costs $15. $$\begin{array} { | c | c | } \hline \begin{array} { c } \text { Number of } \\\text { Car Washes } \\\text { Per Month }\end{array} & \begin{array} { c } \text { Total Monthly } \\\text { Benefit from } \\\text { Car Washes }\end{array} \\\hline 0 & \$ 0 \\\hline 1 & \$ 20 \\\hline 2 & \$ 36 \\\hline 3 & \$ 48 \\\hline 4 & \$ 56 \\\hline 5 & \$ 60 \\\hline\end{array}$$ What is the marginal cost of the 5^th car wash each month?

A) $15
B) $14
C) $12
D) $4