For multiple orders, the calculation method of closing profit and loss is (closing price-opening price) x lots x contract multiplier.

For opening empty orders, the calculation method of closing profit and loss is (opening price-closing price) x lots x contract multiplier.

After synthesis, regardless of multiple orders or empty orders, the closing profit and loss is calculated as (selling price-buying price) x lots x contract multiplier.

The multiplier of soybean futures contract is 10 ton/lot.

Therefore, liquidation gain and loss =(2020-2030)x5x 10=-500.

The profit and loss of the position is calculated before the closing, which is a comparison between the opening price and the current market price. If it doesn't close now, quote 2050.

Then the current position profit and loss is (2020-2050) x15x10 =-4500.

However, according to stem information, when debt-free settlement is made after closing, it is based on the settlement price.

The position profit and loss is calculated as (2020-2040) x15x10 =-3000.

So the answer is a.