While underway, which of the following would be the FIRST step in reversing a direct reversing large, slow-speed, main propulsion, diesel engine?

Correct Answer: Option B — Set the fuel rack to zero.

Cutting off fuel delivery by setting the fuel rack to zero immediately halts combustion energy input before any reversing maneuver begins, preventing destructive overspeed, backfiring, or severe mechanical shock within the propulsion drive train during shaft deceleration.