The speed of sound in a mixture of $$1$$ mole of Helium, molar mass $$4\,\text{g mol}^{-1}$$, and $$2$$ moles of oxygen, molar mass $$32\,\text{g mol}^{-1}$$, at $$27^\circ\text{C}$$ is nearly

A

$$318\,\text{m s}^{-1}$$

B

$$332\,\text{m s}^{-1}$$

C

$$381\,\text{m s}^{-1}$$

D

$$401\,\text{m s}^{-1}$$