What Is the Free Energy Change, ΔG°, for the Equilibrium

What is the free energy change, ΔG°, for the equilibrium between hydrogen iodide, hydrogen, and iodine at 453°C? (R = 8.314 J/K• mol) 2HI(g) H₂(g) + I₂(g) K_c = 0.020 at T = 453°C

A) 6.4 kJ/mol
B) 8.8 kJ/mol
C) 15 kJ/mol
D) 19 kJ/mol
E) 24 kJ/mol