There are three vectors $\vec{P}$, $\vec{Q}$ and $\vec{R}$. The angle between $\vec{P}$ and $\vec{Q}$ is $60^\circ$ and $\vec{R}$ is perpendicular to the plane containing $\vec{P}$ and $\vec{Q}$. Consider the relations:

(a) $\vec{P}+\vec{Q}+\vec{R}=0$

(b) $\vec{P}\times\vec{Q}=\vec{R}$

(c) $\vec{P}\times\vec{R}=\vec{Q}$

The possible relations are