Concept:We use dzdy=dz/dxdy/dx and simplify inverse trigonometric functions.Explanation:Let y=tan−1(x1+x2−1) and z=sin−1(1+x22x).Rationalising the expression in y, we get:x1+x2−1=1+x2+1xUsing the standard identity:tan−1(1+x2+1x)=21tan−1xTherefore:y=21tan−1xDifferentiating with respect to x:dxdy=2(1+x2)1Now simplify z using the identity:sin−1(1+x22x)=2tan−1xSo:z=2tan−1xDifferentiating with respect to x:dxdz=1+x22Hence:dzdy=1+x222(1+x2)1=41Thus, the required derivative is 41.Answer:41 (Option B).