One kg of a diatomic gas is at a pressure of $$8 \times 10^4$$ N/m$$^2$$. The density of the gas is $$4$$ kg/m$$^{-3}$$. What is the energy of the gas due to its thermal motion?

A

$$3 \times 10^4$$ J

B

$$5 \times 10^4$$ J

C

$$6 \times 10^4$$ J

D

$$7 \times 10^4$$ J