【单选题】In an export business, 50% L / C and 50% D / P shall be adopted for payment. In order to secure the collection of foreign exchange, it shall be stipulated in the contract ( )
A.
to draw two drafts , each with a set of commercial documents
B.
to draw two drafts , clean draft under L/C,documentary draft under collection
C.
to draw two drafts , clean draft under collection ,documentary draft under L/C
D.
to draw two drafts , clean draft used under both L/C and collection