Answer
The equilibrium is reached at $(v)$.
Work Step by Step
Since the figures are sequential in time, the equilibrium will be reached when the amount of each molecule is constant.
From figure (i) to (v) we can notice a decrease in the number of $H_2$ and $I_2$ molecules, indicating that the reaction is occuring favoring the right side.
But, between $(v)$ and $(vi)$, these numbers are constant, which means that they are being produced and consumed at the same rate (equilibrium).
