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

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

According to COLREGS Rule 35(i), a power-driven pilot vessel on station and engaged in pilotage duties sounds one prolonged blast followed by four short blasts to distinguish its unique operational profile from standard power-driven merchant traffic in fog.