If a reverse-osmosis freshwater generating unit has a high salinity alarm associated with the freshwater outlet, what should be done?

Correct Answer: Option B — The membrane modules should be flushed and cleaned.

High salinity in the freshwater output indicates that the membrane modules are failing to reject salt effectively, often due to fouling or degradation. Flushing and cleaning the membranes is the standard corrective action to restore the rejection rate and bring the distillate salinity back within acceptable operational limits.