Introduction:
The given graph represents the attainment of equilibrium for the reaction A(g) = 2C(g) + B(g). The graph provides information about the concentrations of A, B, and C gases at different points in time during the reaction. By analyzing the graph, we can determine the correct option.

Key Observations:
1. Initially, the concentration of A is high, and there is no B or C present.
2. As time progresses, the concentration of A decreases, while the concentrations of B and C increase.
3. At a certain point, the concentrations of B and C reach their maximum values, while the concentration of A continues to decrease.
4. Eventually, the concentrations of B and C start to decrease, while the concentration of A increases.

Explanation:
Based on the key observations, we can draw the following conclusions:

1. Initially, only A is present in high concentration. As the reaction proceeds, A molecules start to react and convert into B and C molecules. This leads to a decrease in A concentration and an increase in B and C concentrations.

2. As the reaction progresses further, the concentrations of B and C reach their maximum values. This indicates that the forward reaction (A → B + C) is still occurring but at a slower rate compared to the reverse reaction (B + C → A).

3. After reaching the maximum concentrations, the concentrations of B and C start to decrease. This suggests that the reverse reaction is now occurring at a faster rate than the forward reaction, causing the concentrations of B and C to decrease.

4. Eventually, the concentrations of B and C decrease to a point where the reverse reaction dominates, and the concentrations of A start to increase again.

Conclusion:
Based on the graph, we can conclude that the equilibrium in the reaction A(g) = 2C(g) + B(g) is reached when the concentrations of B and C reach their maximum values, and the concentrations of B and C start to decrease while the concentration of A increases. This indicates that the reaction is reversible, with the forward and reverse reactions occurring simultaneously until equilibrium is achieved.