Correct option is (C) -cot x + tan x + C
\(\int \frac{dx}{\sin^2x.\cos^2x}\)
\(= \int \frac{(\sin^2x + \cos^2x)}{\sin^2x.\cos^2x}\)
\(= \int \frac{\sin^2x}{\sin^2x. \cos^2x} dx + \int \frac{\cos^2 x}{\sin^2x. \cos^2x}dx\)
\(=\int\frac{dx}{\cos^2x}dx+\int \frac{dx}{\sin^2x}\)
\(= \int \sec^2xdx+ \int \text{cosec}^2x dx\)
\(= \tan x - \cot x+ C\)
\(= - \cot x+\tan x+ C\)