JEE Math Practice Question

If $$\theta $$1 and $$\theta $$2 be respectively the smallest and the largest values of $$\theta $$ in (0, 2$$\pi $$) - {$$\pi $$} which satisfy the equation, 2cot2$$\theta $$ - $${5 \over {\sin \theta }}$$ + 4 = 0, then $$\int\limits_{{\theta _1}}^{{\theta _2}} {{{\cos }^2}3\theta d\theta } $$ is equal to :

1. A.$${\pi \over 9}$$
2. B.$${{2\pi } \over 3}$$
3. C.$${{\pi } \over 3}$$
4. D.$${\pi \over 3} + {1 \over 6}$$