Concept:A function is increasing when its derivative is positive.Explanation:Given f(x)=[x(x−2)]2=x2(x−2)2.Differentiate using the product rule.f′(x)=2x(x−2)2+2(x−2)x2=2x(x−2)(x−2+x)=4x(x−1)(x−2).For f(x) to be increasing, f′(x)>0.So 4x(x−1)(x−2)>0, which simplifies to x(x−1)(x−2)>0.Using the sign scheme for critical points 0, 1, and 2, the product is positive for x∈(0,1)∪(2,∞).Answer:x∈(0,1)∪(2,∞), i.e. option D.