What type of sonar equipment can be deployed from helicopters to detect submerged submarines?

The correct answer is dipping sonar, which is specifically designed for deployment from helicopters to locate submerged submarines. Dipping sonar operates by lowering a sonar transducer into the water while the helicopter hovers above. This allows the sonar system to actively search for underwater objects, including submarines, by emitting sound waves and listening for their echoes.

Dipping sonar is advantageous in a number of ways. It can provide real-time data and can be used in both shallow and deep waters. This method also enhances the helicopter's capability to perform anti-submarine warfare, allowing for rapid response and flexible deployment.

Other options like passive sonar typically involve fixed installations or buoys and are not designed for helicopter deployment. Controlled sonar, while it may refer to sonar systems that are manageably used, does not specifically correlate to a type that can be deployed from a helicopter for detecting submarines. Therefore, dipping sonar is the most appropriate choice given the question's context.