Concept:Use the derivative of tan−1(x5+x51).Explanation:Let u=x5+x51.Then dxdu=5x4−x65=x65(x10−1).Also, 1+u2=1+(x5+x51)2=x10+3+x101=x10x20+3x10+1.So dxdtan−1u=1+u2du/dx.Substituting the values: x65(x10−1)⋅x20+3x10+1x10=x20+3x10+15x4(x10−1).Hence the given integrand is 51 times this derivative.Therefore, ∫x20+3x10+1x4(x10−1)dx=51tan−1(x5+x51)+c.Answer:Option B: 51tan−1(x5+x51)+c