Feed water pumps take water from the:

Feed water pumps are designed to take water from the source where it has been preheated and made ready to enter the boiler. The open feedwater heater is a critical component in this process. In an open feedwater heater, water from the condensate return system is mixed with steam, which allows for effective heat transfer and raises the temperature of the water before it goes into the boiler. This preheating step increases the efficiency of the boiler, as warmer water requires less energy to turn into steam.

This option aligns with the operational sequence of a steam system, where maximizing the temperature of the feedwater prior to entering the boiler enhances overall efficiency. Therefore, choosing the open feedwater heater as the source for feed water pumps is correct, as it reflects the proper functioning of the system in preparing water for steam generation.