The correct answer is B: By re-evaluating the station whenever an item in the transmitter or antenna system is changed. You can make sure your station stays in compliance with RF safety regulations by re-evaluating whenever an item in the transmitter or antenna system is changed. Any change (power, frequency, antenna type, location, etc.) can affect RF exposure, so you must reassess. For amateur radio operators, this is an ongoing responsibility. Understanding this helps maintain compliance as your station evolves. RF exposure assessment isn't a one-time thing.