The formation of a complex ion occurs in several steps. Given the series of steps and equilibrium constants below, calculate the equilibrium constant for:

A³⁺(aq) + 2NH₂⁻(aq) ⇌ A(NH₂)₂⁺(aq)

A³⁺(aq) + NH₂⁻(aq) ⇌ ANH₂²⁺(aq) K₁ = 200
ANH₂²⁺(aq) + NH₂⁻(aq) ⇌ A(NH₂)₂⁺(aq) K₂ = 125

What is the equilibrium constant for the overall reaction?

A) 25,000
B) 50,000
C) 100,000
D) 200,000