Which helicopter introduced in 1971 took on mine countermeasures as its primary mission?

The helicopter that was introduced in 1971 and took on mine countermeasures as its primary mission is the CH-53A Sea Stallion. This heavy-lift helicopter was designed to support a variety of missions for the U.S. Navy and Marine Corps, including amphibious assaults, tactical troop transport, and mine countermeasures operations. Its large size and powerful engines allowed it to carry significant payloads and perform in challenging environments, making it well-suited for the tasks involved in mine warfare, particularly in maritime settings.

The other helicopters mentioned do not specifically align with this mission focus. The UH-1 Iroquois, known for its versatility, primarily served as a utility helicopter and was not specifically designed with mine countermeasures as a central function. The AH-64 Apache is an attack helicopter used mainly for close air support and reconnaissance rather than mine countermeasures. The SH-60 Seahawk is indeed involved in anti-mine operations but was introduced later and serves a variety of missions, not solely focused on countering mines. Thus, the CH-53A Sea Stallion stands out as the correct answer for its specialized role in mine countermeasures from its inception.