At High Temperatures Boron Carbide Vaporizes According to the Equation

At high temperatures boron carbide vaporizes according to the equation B₄C(s) ⇌ 4 B(g) + C(s)
Which equation describes the relationship between ΔG° and ΔG for this reaction?

A) ΔG = ΔG° + R T ln (p_B ∙ [C]/[B₄C])
B) ΔG = ΔG° + R T ln p_B
C) ΔG = ΔG° + 4 R T ln p_B
D) ΔG = ΔG° - 4 R T ln p_B