Ans: D
$\begin{array}{cl}
& \dfrac{\cos A}{\sin A} + \dfrac{\sin A}{\cos A} \\
= & \dfrac{\cos^2A + \sin^2A}{\sin A \cos A} \\
= & \dfrac{1}{\sin A \cos A}
\end{array}$
$\begin{array}{cl}
& \dfrac{\cos A}{\sin A} + \dfrac{\sin A}{\cos A} \\
= & \dfrac{\cos^2A + \sin^2A}{\sin A \cos A} \\
= & \dfrac{1}{\sin A \cos A}
\end{array}$
