If $\hat{u}$ and $\hat{v}$ are unit vectors and $\theta$ is the acute angle between them, then $2 \hat{u} \times 3 \hat{v}$ is a unit vector for :

Question

( A ) exactly two values of $\theta$
( B ) exactly one value of $\theta$
( C ) more than two values of $\theta$
( D ) no value of $\theta$