The Following Pictures Represent Mixtures of A₂B₄ Molecules and AB₂

The following pictures represent mixtures of A₂B₄ molecules and AB₂ molecules,which interconvert according to the equation A₂B₄ ⇌ 2 AB₂.If mixture (1) is at equilibrium,which of the other mixtures are also at equilibrium?

A) mixture (2)
B) mixture (3)
C) mixture (4)
D) None of the other mixtures are at equilibrium.