Which of the following is the most economical payment for both buyers and sellers?
A、D/A
B、L/C
C、T/T
D、D/P

A.具有只对专业技术本身负责的纯技术性
B.专业技术类职位与其他职位相比具有不可替代性
C.技术权威性
D.技术层面