The Table Below Shows Output, Marginal Cost, and Average Variable

The table below shows output, marginal cost, and average variable cost for the production of pairs of shoes. All costs are in dollars. $$\begin{array}{l}\begin{array} { | l | l | l | } \hline \text { Output } & \begin{array} { l } \text { Marginal } \\\text { Cost }\end{array} & \begin{array} { l } \text { Average } \\\text { Variable Cost }\end{array} \\\hline 50 & 60 & 140 \\\hline 70 & 45 & 115 \\\hline 90 & 35 & 95 \\\hline 110 & 30 & 80 \\\hline 130 & 35 & 65 \\\hline 150 & 60 & 60 \\\hline 170 & 105 & 65 \\\hline 190 & 180 & 75 \\\hline 210 & 230 & 90 \\\hline 230 & 290 & 110 \\\hline\end{array}\\\text { TABLE 7- } 6\end{array}$$
-Refer to Table 7- 6. The firm's marginal product of its variable factor is maximized when it produces units of output.

A) 100
B) 110
C) 170
D) 50
E) 90