Concept:If x+y+z=0, then x3+y3+z3=3xyz.Explanation:First, consider the numerator: (a2−b2)+(b2−c2)+(c2−a2)=0.Hence, numerator =3(a2−b2)(b2−c2)(c2−a2).Similarly, denominator: (a−b)+(b−c)+(c−a)=0.Hence, denominator =3(a−b)(b−c)(c−a).Now the expression becomes 3(a−b)(b−c)(c−a)3(a2−b2)(b2−c2)(c2−a2).Factor each difference of squares: a2−b2=(a−b)(a+b), b2−c2=(b−c)(b+c), c2−a2=(c−a)(c+a).Cancel the common factor 3(a−b)(b−c)(c−a) from numerator and denominator.The result is (a+b)(b+c)(c+a).Answer:A. (a+b)(b+c)(c+a)