Concept:Use algebraic identities and standard trigonometric integrals to simplify the integrand.Explanation:Given integral is ∫sin2xcos2xsin6x+cos6xdxUse the identity a3+b3=(a+b)3−3ab(a+b).Take a=sin2x and b=cos2x.Then sin6x+cos6x=(sin2x+cos2x)3−3sin2xcos2x(sin2x+cos2x)Since sin2x+cos2x=1, we get sin6x+cos6x=1−3sin2xcos2xDivide by sin2xcos2x: sin2xcos2xsin6x+cos6x=sin2xcos2x1−3Also, sin2xcos2x1=sec2x+csc2xSo the integral becomes ∫(sec2x+csc2x−3)dxIntegrate term by term: ∫sec2xdx=tanx,∫csc2xdx=−cotx,∫3dx=3xThus, ∫sin2xcos2xsin6x+cos6xdx=tanx−cotx−3x+cAnswer:tanx−cotx−3x+c, hence Option B.