If I=∫0π/2sinnxsinnx+cosnxdxI = \int_{0}^{\pi/2} \frac{\sin^n x}{\sin^n x + \cos^n x} dxI=∫0π/2sinnx+cosnxsinnxdx, what is the value of III regardless of the value of n>0n > 0n>0?
π/2\pi/2π/2
π/4\pi/4π/4
111
n/2n/2n/2