The equilibrium constant $$K_c$$ for trimerization of phenyl acetylene to triphenyl benzene is 3.0 at 310 K. If at equilibrium 0.9 mol $$\text{dm}^{-3}$$ of triphenyl benzene is present, concentration of phenyl acetylene at equilibrium is

A

$$\frac{1}{3}$$ mol $$\text{dm}^{-3}$$

B

3.0 mol $$\text{dm}^{-3}$$

C

1.732 mol $$\text{dm}^{-3}$$

D

0.67 mol $$\text{dm}^{-3}$$