Let $g^{\prime }\left(x\right)$ be continuous for all real $x$. What is the average value of $g^{\prime }\left(x\right)$ on the interval $[2,7]$?

• A. $\frac{g\left(2\right)+g\left(7\right)}{2}$
• B. $\frac{g^{\prime }\left(2\right)+g^{\prime }\left(7\right)}{2}$
• C. $\frac{g\left(7\right)-g\left(2\right)}{5}$
• D. $\frac{g^{\prime }\left(7\right)-g^{\prime }\left(2\right)}{5}$