Difficult# Trig Derivatives Taken Up Another Notch

APCALC-DJXQBB

Which of the following are equivalent to $\cfrac{d}{dx} (\sin x)$?

I.$y'$ when $y=\sin x +\cos \pi$II.$\cfrac{dy}{dx}$ when $y-\cos x \cdot \tan x = 15$III.$f'(x)$ when $f(x)=\sin x(\cos^2 (3x) + \sin^2 (3x))$