The correct answer is (c). A letter of credit is a document issued by a bank at the request of an importer, which guarantees payment to an exporter on the condition that the exporter has met certain conditions, such as shipping the goods and providing proof of shipment. The letter of credit is a binding contract between the bank and the importer, and the bank is obligated to pay the exporter even if the importer does not pay.
(a) is incorrect because the exporter is not the one who issues the letter of credit.
(b) is incorrect because the importer is not the one who issues the letter of credit.
(d) is incorrect because the shipping company is not the one who issues the letter of credit.