The correct answer is B) the vessel is not making way. The reasoning behind this is that when a work stage is rigged over the side of a vessel, the seaman working on the stage is only permitted to do so when the vessel is not making way (i.e., not underway or not moving). This is a safety requirement to prevent the seaman from being thrown off the work stage if the vessel were to move unexpectedly. The other options are incorrect because wearing a life jacket alone (A) or wearing a safety harness (C and D) does not eliminate the risk of the seaman being thrown off the work stage if the vessel is underway. The key requirement is that the vessel must be stationary, or not making way, when a seaman is working on the rigged work stage.