The angle between the vectors $\hat{i}-2 \hat{j}+\hat{k}$ and $3 \hat{i}+2 \hat{j}+\hat{k}$ is:

0 $\frac{\pi}{4}$ $\pi$ $\frac{\pi}{2}$

$\frac{\pi}{2}$

The correct answer is Option (4) → $\frac{\pi}{2}$