Concept:Rewrite the integrand as tannxsec2x and use substitution.Explanation:Given integral: I=∫cosn+2xsinnxdxSplit the powers of cosx: cosn+2xsinnx=cosnxsinnx⋅cos2x1Use cosxsinx=tanx and cos2x1=sec2x:cosn+2xsinnx=tannxsec2xTherefore, I=∫tannxsec2xdxLet t=tanx. Then dt=sec2xdx.So, I=∫tndt=n+1tn+1+CSubstitute back t=tanx:I=n+1tann+1x+CAnswer:Option D: n+1tann+1x+C