Concept:Simplify the nested trigonometric expression using cot2θ and then differentiate the resulting simple function.Explanation:Let θ=cot−11−x1+x.Then cot2θ=1−x1+x.Add 1 to both sides:1+cot2θ=1+1−x1+x=1−x2.Using 1+cot2θ=csc2θ, we get:csc2θ=1−x2.Therefore, sin2θ=21−x.Since y=sin2θ, we substitute directly:y=21−x.Differentiate with respect to x:dxdy=−21.Answer:dxdy=−21, so the correct option is A. 2−1.