Table 10-3
​
​ -Refer to Table 10-3

Table 10-3
​
​
$$\begin{array} { | c | c | c | c | } \hline \begin{array} { c } \text { Quantity } \\\text { (Units) }\end{array} & \begin{array} { c } \text { Private Value } \\\text { (Dollars) }\end{array} & \begin{array} { c } \text { Private Cost } \\\text { (Dollars) }\end{array} & \begin{array} { c } \text { External Benefit } \\\text { (Dollars) }\end{array} \\\hline 1 & 22 & 12 & 10 \\\hline 2 & 20 & 15 & 10 \\\hline 3 & 18 & 18 & 10 \\\hline 4 & 16 & 21 & 10 \\\hline 5 & 14 & 24 & 10 \\\hline 6 & 12 & 27 & 10 \\\hline\end{array}$$
-Refer to Table 10-3. The social value of the 4^th unit of output that is produced is

A) $10.
B) $16.
C) $26.
D) $30.