88J2 C
 Which of the following statements concerning SITOR (NBDP) communications is true?
A. FEC transmissions are made in data groups consisting of three-character blocks.
B. FEC transmissions require a "phasing" or "handshaking" process prior to character transmission.
C. FEC transmissions rely upon an error correction technique, which transmits each character twice.
D. FEC transmissions rely upon parity and "repeat requests" to ensure error correction.
