The numerical value of ( 1 + 1 ) ( 1 - 1 ) is?

Answer: Option C

$$\begin{array}{rl}& \left(\frac{1}{\cos \theta }+\frac{1}{\cot \theta }\right)\left(\frac{1}{\cos \theta }-\frac{1}{\cot \theta }\right)\\ & =\left(\sec \theta +\tan \theta \right)\left(\sec \theta -\tan \theta \right)\\ & ={\sec }^2\theta -{\tan }^2\theta \left[1+{\tan }^2\theta ={\sec }^2\theta \right]\\ & =1\end{array}$$