Answer:
c. the well-being of sellers.
Explanation:
A surplus is the amount by which the quantity supplied of a good exceeds the quantity demanded of the good.
Producer surplus is the amount a buyer is willing to pay for a good minus the cost of producing the good.
On the other hand, consumer surplus is the amount a buyer is willing to pay for a good minus the amount the buyer actually pays for it.
Hence, an export subsidy will increase producer surplus.
In conclusion, producer surplus directly measures the well-being of sellers.
