Concept:Composite functions and verifying options by substitution.Explanation:Given g(x)=x2+x−2 and 21(g∘f)(x)=2x2−5x+2.Multiply both sides by 2 to get (g∘f)(x)=4x2−10x+4.Since g(f(x))=(f(x))2+f(x)−2, we need (f(x))2+f(x)−2=4x2−10x+4.Check option B: f(x)=2x−3.Then g(f(x))=(2x−3)2+(2x−3)−2.Expand: 4x2−12x+9+2x−3−2=4x2−10x+4.This matches the required expression, so option B is correct.Answer:f(x)=2x−3Correct option: B.