Concept:Use the quotient rule for differentiating vu.Explanation:Let u=x and v=x+1.Then dxdu=1 and dxdv=1.Quotient rule: dxd(vu)=v2vdxdu−udxdv.Substitute the values:dxd(x+1x)=(x+1)2(x+1)(1)−x(1).Simplify the numerator:=(x+1)2x+1−x=(x+1)21.Answer:(x+1)21, which is option D.