Find the second derivative of $f\left(x\right)=2\sin x-3\cos x$ with respect to $x$.

$\frac{d^2}{d{x}^2}\left(f\left(x\right)\right)=2\sin x-3\cos x$

$\frac{d^2}{d{x}^2}\left(f\left(x\right)\right)=-2\sin x-3\cos x$

$\frac{d^2}{d{x}^2}\left(f\left(x\right)\right)=-2\sin x+3\cos x$

$\frac{d^2}{d{x}^2}\left(f\left(x\right)\right)=2\sin x+3\cos x$