The correct answer is C) jacket water pump suction line. The outlet from an expansion tank of a closed fresh water cooling system should be piped to the jacket water pump suction line. This is because the expansion tank serves to accommodate the expansion of the cooling water as it heats up, and the water from the expansion tank needs to be returned to the suction side of the jacket water pump to maintain the proper water level and pressure in the closed cooling system. The other options are incorrect because: A) the cylinder jacket inlet main is not the appropriate location for the expansion tank outlet, B) the heat exchanger inlet connection is not the correct point for the expansion tank outlet, and D) the cylinder head water outlet header is also not the proper location for the expansion tank outlet in a closed fresh water cooling system.