Due to recent changes in infrastructure， a four-node cluster has been split into two locations， but is still listed as a single site in HACMP. The location split has proceeded smoothly， the only exception being the serial heartbeats. There are constant errors causing the serial network to go up and down. What is the best solution to resolve this issue？（）

A. Install the dialback failsafe optional filesets.
B. Change the speed parameter in "smitty tty" to be 38400，8，N，1.
C. Install additional rsct filesets required for non null modem connections.
D. Change the parameters in the Network Module to stop RSCT from changing the speed of the line.