BOTH INTERNATIONAL & INLAND A fog signal of one prolonged blast followed by four short blasts would mean the presence of a __________.

Correct Answer: Option C — power-driven pilot vessel on station underway

Per COLREGS Rule 35(i), a power-driven pilot vessel engaged on pilotage duty sounds one prolonged followed by four short blasts as an identity signal in restricted visibility, supplementing its standard power-driven vessel fog signals.