$$\begin{array} { c c } \text { Output } & \text { Price } \\\hline 1 & \$ 30 \\2 & \$ 27 \\3 & \$ 24 \\4 & \$ 21 \\5 & \$ 18\end{array}$$

Multiple Choice

$$\begin{array} { c c } \text { Output } & \text { Price } \\\hline 1 & \$ 30 \\2 & \$ 27 \\3 & \$ 24 \\4 & \$ 21 \\5 & \$ 18\end{array}$$
-The marginal revenue that would be derived from producing a fourth unit of output is

A) $30
B) $24
C) $21
D) $18
E) $12