A Series of Four Equilibrium Steps Can Be Defined for the Following

A series of four equilibrium steps can be defined for the following overall reaction that occurs in aqueous solution:
Cu²⁺ + 4 NH₃ $\leftrightarrows$ [Cu(NH₃) ₄]²⁺ $\quad$ $\quad$ K_overall
Cu²⁺ + NH₃ $\leftrightarrows$ [Cu(NH₃) ]²⁺ $\quad$ $\quad$ $\quad$ K₁
[Cu(NH₃) ]²⁺ + NH₃ $\leftrightarrows$ [Cu(NH₃) ₂]²⁺ $\quad$ K₂
etc.
What is true about K₄?

A) K₄ = K_overall
B)
C)
D) K₄ = K₁K₂K₃
E)