JEE Math Practice Question

If $${I_n} = \int\limits_{{\pi \over 4}}^{{\pi \over 2}} {{{\cot }^n}x\,dx} $$, then :

1. A.$${1 \over {{I_2} + {I_4}}},{1 \over {{I_3} + {I_5}}},{1 \over {{I_4} + {I_6}}}$$ are in A.P.
2. B.I2 + I4, I3 + I5, I4 + I6 are in A.P.
3. C.$${1 \over {{I_2} + {I_4}}},{1 \over {{I_3} + {I_5}}},{1 \over {{I_4} + {I_6}}}$$ are in G.P.
4. D.I2 + I4, (I3 + I5)2, I4 + I6 are in G.P.