Answer: b.
damages should be measured by the difference between the contract price and the market price of the goods at the port of shipment
Explanation: Because the contract has already been initiated and was defaulted by the seller. The Judge would ask him to pay for damages. And this will be measured by subtracting the contract price of the goods from the market price. I.e the price the goods would gave been sold and the price the seller accepted to sell to the buyer according to the contract they signed.