9708/11 Economics May Jun 2023 Online Test | Cambridge AS and A Level MCQ

In the diagram S and ${S_1}$ are the supply curves for an agricultural product in years 1 and 2 respectively. D is the demand curve in years 1 and 2.
In year 1 the government purchased an amount necessary to ensure that the price was OP.
The price is held at OP in year 2.
How much more must the government buy in year 2 than it bought in year 1?