Given the Total Cost Schedule Below, at What Level of Output

Multiple Choice

Given the total cost schedule below, at what level of output is the average cost the lowest?
$$\begin{array} { | l | l | l | l | l | l | l | l | } \hline \text { Output } & 0 & 1 & 2 & 3 & 4 & 5 & 6 \\\hline \text { Total Cost } & 10 & 20 & 24 & 27 & 40 & 55 & 90 \\\hline\end{array}$$

A) 2
B) 3
C) 4
D) 5