N molecules, each of mass m, of gas A and 2 N molecules, each of mass 2 m, of gas B are contained in the same vessel which maintained at a temperature T. The mean square of the velocity of molecules of B type is denoted by n2 and the mean square of the X component of the velocity of A type is denoted by w2, then

• A. 2
• B. 1
• C. 1/3
• D. 2/3