The Following Table Shows the Total Revenue and Total Cost

The following table shows the total revenue and total cost (in dollars) from different sales volumes of the good.
Table 2-1
$\begin{array} { | c | c | c | c | } \hline \text { Price } & \text { Quantity } & \text { Total Revenue } & \text { Total Cost } \\\hline 15 & 1 & 15 & 3 \\\hline 14 & 2 & 28 & 7 \\\hline 13 & 3 & 39 & 12 \\\hline 12 & 4 & 48 & 18 \\\hline 11 & 5 & 55 & 25 \\\hline 10 & 6 & 60 & 33 \\\hline\end{array}$

-Refer to Table 2-1. What is the marginal profit of the firm from the sale of the 3rd unit of the good?

A) $9
B) $6
C) $2
D) $5
E) $21