A _________________ is equipped with two quarter-turn ball valves so that the flow of water to each of the split lines can be controlled independently.

A gated wye is specifically designed to facilitate the control of water flow in multiple directions while allowing for independent operation of each line. This configuration features two quarter-turn ball valves, making it possible to manage the flow to each of the split lines separately and efficiently. This dual-control design is essential in firefighting scenarios where flexibility and the ability to direct water as needed are critical.

In contrast, a dual-line adapter typically connects two hose lines but may not provide independent flow control for each line. A splitter serves a similar function to a gated wye but usually lacks the ability to independently control flow, instead dividing the flow equally among outputs without individual shut-off capabilities. A manifold, while it may also feature multiple outlets, is generally used for distributing water among several lines but might not have the same level of flow control and flexibility that a gated wye offers.

Thus, the gated wye's unique design equips it with the necessary features for independent flow control, making it the correct choice in this context.