The Formation Constant for the Reaction Ag⁺(aq) + 2NH₃(aq) $\degree$ C What Is

The formation constant for the reaction Ag⁺(aq) + 2NH₃(aq) Ag(NH₃) ₂⁺(aq) is K_f = 1.7 *10⁷ at 25 $\degree$ C. What is $\Delta$ G $\degree$ at this temperature?

A) -1.5 kJ
B) -3.5 kJ
C) -18 kJ
D) -23 kJ
E) -41 kJ