Math Chapter Wise Modern Algebra English MCQ PGT 2005 Q.Which of the following is a group? A(Z, *) where a*b = ab ∀a, b∈Z B(Z, *) where a*b = a–b ∀a, b∈Z C(R, *) where a*b = ab ∀a, b∈R+ D(Z, *) where a*b = ab ∀a, b∈Z Show answer Correct answer: (R, *) where a*b = ab ∀a, b∈R+