Which of the Following Is True

Which of the following is true?

A) Investment bankers earn fees based on the success of their placements when they underwrite using a best-efforts basis.
B) Investment bankers earn fees based on the success of their placement when they underwrite using firm-commitment basis.
C) With best-efforts underwriting,investment bankers act as principals because they purchase securities from the issuer and sell them at a higher price.
D) An investment banker is acting as an agent when conducting a firm-commitment offering of securities.