\(\begin{array}{c|c}
\text{Units of variable factor} & \text{Total
Product} \\
\hline
1 & 25 \\
\hline
2 & 31 \\
\hline
3 & 40 \\
\hline
4 & 48 \\
\hline
5 & 55 \\
\end{array}\)



The marginal product at the fifth variable factor is

• A.7
• B.6
• C.5
• D.9
• E.