Q. Which of the following two sets are equal?

• (A) a = {1, 2} and b = {1}
• (B) a = {1, 2} and b = {1, 2, 3}
• (C) a = {1, 2, 3} and b = {2, 1, 3}
• (D) a = {1, 2, 4} and b = {1, 2, 3}