JEE Math Practice Question

If $$\int {{{\cos xdx} \over {{{\sin }^3}x{{\left( {1 + {{\sin }^6}x} \right)}^{2/3}}}}} = f\left( x \right){\left( {1 + {{\sin }^6}x} \right)^{1/\lambda }} + c$$ where c is a constant of integration, then $$\lambda f\left( {{\pi \over 3}} \right)$$ is equal to

1. A.$${9 \over 8}$$
2. B.2
3. C.-2
4. D.$$-{9 \over 8}$$