A.
2 single channel TCAS computer, 2 TCAS antennas, 2 S mode ATC transponder, 1 active, another alternate.
B.
1 single channel TCAS computer, 2 TCAS antennas, 2 S mode ATC transponder, 1 active, another alternate.
C.
1 single channel TCAS computer, 2 TCAS antennas, 1 S mode ATC transponder, 1 active, another alternate.