The correct answer is A) pushing the switch lever arm while the winch is running. Limit switches on gravity davits should be tested by physically pushing the switch lever arm while the winch is running to ensure the switch is functioning properly. This tests the switch's ability to cut power to the winch motor when the lever arm is activated, which is the critical safety function of the limit switch. The other options are incorrect because B) shutting off current to the winch does not test the switch itself, and C) having engineers test the switch from the engine room does not directly verify the switch's operation.