Final answer:
In boating, the appropriate signal to give when passing a boat on your port side is one short blast. This signal indicates that you intend to leave the other boat on your port side and pass behind it.
Step-by-step explanation:
The appropriate signal to give in a head-on, crossing, or overtaking situation when passing another boat on your port side is one short blast (option a). This signal indicates that you intend to leave the other boat on your port side and pass behind it. When passing on the starboard side, the appropriate signal is two short blasts. Signals are important for communication and ensuring safe navigation on the water.