Refer to the Information Provided in Table 8 -Refer to Table 8

Refer to the information provided in Table 8.4 below to answer the question(s) that follow.
Table 8.4
$$\begin{array} { c c c c } \hline \text { Produce } & \text { Using Techniques } & \text { Units of Variable K } & \text { Inputs L } \\\hline 1 \text { unit of output } & \text { A } & 4 & 4 \\\hline & \text { B } & 2 & 6 \\\hline 2 \text { units of output } & & & \\\hline & \text { A } & 7 & 6 \\\hline& \text { B } & 4 & 10 \\\hline 3 \text { units of output } &\text { A } &8 & 6 \\\hline &\text { B } & 6& 11 \\\hline\end{array}$$
-Refer to Table 8.4. Assuming the price of capital (K) is $10 per unit and the price of labor (L) is $5 per unit, the marginal cost of producing the third unit of output is

A) $15.
B) $20.
C) $25.
D) indeterminate from this information.