The correct answer is C) starting the disengaged windlass at high speed. When an anchor becomes jammed in the hawsepipe, the simplest method to free it is to start the disengaged windlass at high speed. This creates a powerful reverse force that can dislodge the anchor from the hawsepipe. The rapid rotation of the windlass drum generates enough torque to pull the anchor free, without requiring additional equipment or tools. The other options are less effective. Greasing the hawsepipe (A) may help lubricate the area, but does not provide the necessary force to pull the anchor out. Rigging a bull rope (B) or prying with a pipe (D) require more time and effort to set up, and may not generate enough pulling power on their own to dislodge a firmly stuck anchor.