A.
The buyer cannot default, L/C and the contract are independent of each other, and the trade under L/C is the document trade.
B.
The seller cannot default, the trade under L/C is the document trade, and L/C and the contract are independent of each other.
C.
The buyer and seller are not allowed to meet, the seller cannot default, and the L/C cannot be changed.
D.
The L/C is irrevocable, and it is independent of the contract, and the trade under the L/C is a document trade.