$$\Delta_r G^\circ$$ at 500 K for substance 'S' in liquid state and gaseous state are +100.7 kcal mol$$^{-1}$$ and +103 kcal mol$$^{-1}$$, respectively. Vapour pressure of liquid 'S' at 500 K is approximately equal to: (R = 2 cal K$$^{-1}$$ mol$$^{-1}$$)

A

100 atm

B

1 atm

C

10 atm

D

0.1 atm