The correct answer is D) Order the dock man to shut down. When a cargo valve jams open during bulk liquid cargo loading, the first action to take is to immediately order the dock personnel to shut down the cargo transfer operation. This is to prevent the uncontrolled flow of cargo, which could lead to spills, damage, or dangerous situations. Calling the owner, operator, or terminal supervisor and taking other actions can follow, but the urgent priority is to stop the cargo flow by shutting down the transfer. The other options, such as running out a fire hose or tripping the pump relief valve, are not the immediate first steps required in this situation.