"One Chinese foreign trade firm, entrusted by a domestic end customer, signed an import contract in its own name with a foreign exporter. The payment was to be made by D/P at sight. When executing the contract, the seller sent the goods and the complete set of documents directly to the end customer without obtaining the agreement from the buyer. After receipt of the goods, the end customer encountered financial difficulty and became unable to make payment. Under such circumstance, the foreign seller believed that the contract was signed by our foreign trade firm in its own name, so the buyer was the trade firm, not the agent of the domestic end customer. According to the payment terms in the contract, the exporter required the trade firm to make payment. Question: Does the Chinese foreign trade firm have the responsibility to make payment? Why?"