If $ 6x = \sec \theta $ and $ \large\frac{6}{x}$$= \tan \theta $, then the value of $36 \bigg(x^2 - \large\frac{1}{x^2} \bigg)$ is __________

Question

$\begin{array}{1 1}(A) \; 6 \\(B)\; 1 \\(C)\;0\\(D)\;2 \end{array}$