A closed vessel contains 10 g of an ideal gas X at 300 K, which exerts 2 atm pressure. At the same temperature, 80 g of another ideal gas Y is added to it and the pressure becomes 6 atm. The ratio of root mean square velocities of X and Y at 300 K is

A

$$2\sqrt{2} : \sqrt{3}$$

B

$$2\sqrt{2} : 1$$

C

$$1 : 2$$

D

$$2 : 1$$