Refer to the Following:
the Capital Stock Is Fixed at 50

Multiple Choice

Refer to the following:
The capital stock is fixed at 50 units, the price of capital is $30 per unit, and the price of labor is $25 per unit.

$$\begin{array} { c c } &\text { Average } \\\text { Output } & \text { Variable Cost }\\\hline 10 & \$ 40 \\20 & 30 \\30 & 45 \\40 & 60 \\\hline\end{array}$$
-How much does the 23rd unit of output add to the firm's total cost?

A) $75
B) $135
C) $750
D) $1,350
E) none of the above