Solve this following

Mark $(\sqrt{ })$ against the correct answer in each of the following:

$\int \frac{1}{\sin ^{2} x \cos ^{2} x} d x=?$

A. $\tan x+\cot x+C$

B. $-\tan x+\cot x+C$

C. $\tan x-\cot x+C$

D. none of these