9-21B2 B
 The sequence ARQ, FEC, SFEC best corresponds to which of the following sequences?
A. One-way communications to a single station, one-way communications to all stations, two-way communications.
B. Two way communications, one-way communications to all stations, one-way communications to a single station.
C. One-way communications to all stations, two-way communications, one-way communications to a single station.
D. Two way communications, One way communications to a single station, One way communications to all stations.
