What class of ship combines the functions of three different classes of ships?

The class of ship that combines the functions of three different classes of ships is the LPD, which stands for Amphibious Transport Dock. LPDs serve multiple roles by integrating the capabilities typically found in various types of amphibious warfare vessels. They can transport and land Marines, their equipment, and supplies via embarked landing craft and helicopters, akin to functions of other vessels in the amphibious group.

Specifically, LPDs can fulfill the roles of a traditional dock landing ship (LSD), convey the ability to move troops like a transport ship, and include aviation assets similar to those found on an aircraft carrier. This multifunctional design allows LPDs to act flexibly in diverse naval operations, making them essential for amphibious assaults and other missions requiring troop movement and logistics support.

The versatility of LPDs is vital in modern naval warfare, as they reduce the need for multiple vessel types, streamline operations, and enhance the efficiency of amphibious missions. Their design enables them to accommodate a broader range of operations than ships dedicated to a single function.