（ ）is the first procedure of L/C business.
选项：

A:The importer and exporter sign a sales contract and make an agreement on L/C payment.;
B:The importer makes application for L/C with his bank. The bank approves the application and issues L/
C: ;
C:The issuing bank advises the documentary credit to the advising bank. ;
D:The advising bank delivers the L/C to the exporter.