The integrating factor of the differential equation $\cos x \frac{d y}{d x}+y \sin x=1$ is

$\sec x$ $\cos x$ $\sec x+\tan x$ $\tan x$

$\sec x$

$\cos x \frac{d y}{d x}+y \sin x=1$ $\Rightarrow \frac{d y}{d x}+y \tan x= \frac{1}{\cos x}$ So P(x) = tan x So integrating factor = I.F = $e^{\int P(x) d x} = e^{\int \tan x d x}$ $=e^{\log \sec x}=\sec x$ Option: 1