In what type of system is the water pressure maintained using a fire pump if necessary?

The correct answer refers to a Wet Standpipe System, which is designed to have water readily available in the standpipe at all times. In a Wet Standpipe System, the piping is constantly filled with water, which means that if there is a demand for water, it is immediately available for firefighters to use. If the municipal water supply pressure is inadequate to meet the system's demand during a fire, a fire pump can be activated to boost the water pressure and ensure that sufficient water flows through the standpipe to suppress the fire.

In contrast, a Dry Standpipe System relies on water being provided from a different source when needed, as it does not have water stored in its pipes at all times. Furthermore, a Manual Standpipe System is operated by firefighters who manually control the flow of water, often needing to rely on external pressurized sources, which may not provide the same immediacy as a Wet Standpipe System with a fire pump. Lastly, a Yard Hydrant System typically provides water for outdoor firefighting and is not directly related to the building's internal standpipe arrangement. Therefore, the specificity of a Wet Standpipe System being maintained with water pressure using a fire pump when necessary makes it the correct answer.