Step 1: Concept
Convert the trigonometric functions into sine and cosine.
Step 2: Analysis
$\sec^2 x + \csc^2 x = \frac{1}{\cos^2 x} + \frac{1}{\sin^2 x} = \frac{\sin^2 x + \cos^2 x}{\sin^2 x \cos^2 x} = \frac{1}{\sin^2 x \cos^2 x}$.
Step 3: Calculation
The expression becomes $\frac{1}{\sin^2 x \cos^2 x} - \sec^2 x \csc^2 x$.
Since $\sec^2 x \csc^2 x = \frac{1}{\cos^2 x} \cdot \frac{1}{\sin^2 x}$, the expression is $\frac{1}{\sin^2 x \cos^2 x} - \frac{1}{\sin^2 x \cos^2 x} = 0$.
Final Answer: (E)