If $z_{1}=r_{1}\left(\cos \theta_{1}+i \sin \theta_{1}\right)$ and $z_{2}=r_{2}\left(\cos \theta_{2}+i \sin \theta_{2}\right)$
are complex numbers, then $\frac{z_{1}}{z_{2}}, z_{2} \neq 0,$ equals which of the following?
(A) $\frac{r_{1}}{r_{2}}\left[\cos \left(\theta_{1}-\theta_{2}\right)+i \sin \left(\theta_{1}-\theta_{2}\right)\right]$
(B) $\frac{r_{1}}{r_{2}}\left[\cos \left(\frac{\theta_{1}}{\theta_{2}}\right)+i \sin \left(\frac{\theta_{1}}{\theta_{2}}\right)\right]$
(C) $\frac{r_{1}}{r_{2}}\left[\cos \left(\theta_{1}+\theta_{2}\right)-i \sin \left(\theta_{1}+\theta_{2}\right)\right]$
(D) $\frac{r_{1}}{r_{2}}\left[\cos \left(\frac{\theta_{1}}{\theta_{2}}\right)-i \sin \left(\frac{\theta_{1}}{\theta_{2}}\right)\right]$