What Development in the 1990's Diminished the Importance of Banker's

What development in the 1990's diminished the importance of banker's acceptances?

A) Export-credit insurance became available and minimized the need for letters of credit.
B) Import-export banks began to refuse to accept the default risk imposed on them by letters of credit.
C) Improved wire-transfers of funds eliminated most of the need for letters of credit.
D) International credit markets replaced letters of credit with derivatives that assumed the risk addressed by letters of credit.