Answer the Question on the Basis of the Following Cost

Answer the question on the basis of the following cost data. $\begin{array}{|c|c|}\hline \text { Output } & \text { Total Cost } \\\hline 0 & \$ 24 \\\hline 1 & 33 \\\hline 2 & 41 \\\hline 3 & 48 \\\hline 4 & 54 \\\hline 5 & 61 \\\hline 6 & 69 \\\hline\end{array}$ The marginal cost of producing the sixth unit of output is

A) $24.
B) $12.
C) $16.
D) $8.