14. In the right quadrilateral pyramid $M-ABCD$, the base $ABCD$ is a rectangle, $MD \perp$ plane $ABCD$, and the length of $MD$ is an integer. The lengths of $MA$, $MC$, and $MB$ are three consecutive even numbers. Then the volume of the right quadrilateral pyramid $M-ABCD$ is ( ).
(A) $24 \sqrt{5}$
(B) 60
(C) $28 \sqrt{5}$
(D) $8 \sqrt{70}$
(E) 66
14. A.

As shown in Figure 13, let's assume
$$
\begin{array}{l}
M A < M C < M B, \\
M D = b, M A = a, \\
M C = a + 2, \\
M B = a + 4 .
\end{array}
$$
$$
\text { Then } a^{2} + (a + 2)^{2} - b^{2} = (a + 4)^{2}
$$
$$
\begin{array}{l}
\Rightarrow (a - 2 + b)(a - 2 - b) = 16 \\
\Rightarrow (a, b) = (7, 3) \\
\Rightarrow A D = 2 \sqrt{10}, C D = 6 \sqrt{2} .
\end{array}
$$

Therefore, \( V = \frac{1}{3} M D \cdot A D \cdot D C = 24 \sqrt{5} \).