The transition moment integral for a rotational transition between $\mathrm{J}=1 ; \mathrm{M}_{\mathrm{J}}=0$ and $\mathrm{J}=2 ; \mathrm{M}_{\mathrm{J}} =0$ states for a diatomic molecule along the $z$ axis is proportional to
(a)$\int_{0}^{\pi} \cos ^{2} \theta\left(3 \cos ^{2} \theta-1\right) d \theta$