Which best describes a dry-barrel fire hydrant:

A dry-barrel fire hydrant is specifically designed so that the barrel does not contain water when it is not in use. This design helps prevent freezing in cold weather, as water left in the hydrant can freeze and damage the hydrant. When the hydrant is activated, water flows from the main supply into the barrel, filling it up for firefighting purposes. This characteristic of having the valve at the bottom allows the water to fill the barrel only when it is in use, making it highly effective in winter conditions.

The other descriptions do not accurately capture the purpose or function of a dry-barrel hydrant. It does not always contain water, as that would defeat its purpose of preventing freezing. It is not exclusively used during winter; rather, it is designed to function effectively in all seasons while avoiding issues with freezing temperatures. Additionally, dry-barrel hydrants do not have a built-in pump mechanism; they rely on the city's water pressure to deliver water when needed.