At What Level of Output Does Marginal Cost Equal Marginal

Multiple Choice

At what level of output does marginal cost equal marginal revenue?

$\begin{array} { c c c } \text { No. Units Produced } & \text { Total Revenue } & \text {Total Costs } \\ 0 & 0 & 0 \\ 10 & 120 & 40 \\ 20 & 200 & 100 \\ 30 & 270 & 170 \\ 40 & 310 & 260 \\ 50 & 330 & 370 \\\end{array}$

A) 10
B) 20
C) 30
D) 40