Concept:Factorise the numerator and cancel common terms with the denominator.Explanation:Write the numerator by taking a2b2 common.a2b4−b2a4=a2b2(b2−a2)Use the difference of squares: b2−a2=(b−a)(b+a)So the expression becomes:ab(a+b)a2b2(b−a)(b+a)Cancel ab and (a+b):=ab(b−a)Expand: ab(b−a)=ab2−a2bAnswer:D.ab2−a2b