Producer surplus is

a. measured using the demand curve for a good

b. always a negative number for sellers in a competitive market.

the amount a seller is paid minus the cost of production

the opportunity cost of production minus the cost of producing goods that go unsold.

The amount a seller is paid minus the cost of production.

Explanation:

Producer surplus refers to the difference between the producer's willingness to accept the price for the product and the price they actually received for the product.

It is calculated as follows:

Producers surplus = Amount a seller received - Cost of production

Or

Producers surplus = Actual amount received - Willingness to accept a price

It is a measure of producers welfare.