How were the teams in the NCDU composed?

The composition of the teams in the Naval Combat Demolition Units (NCDU) consists of six-man teams of volunteers from the Navy Construction Battalion, commonly known as the Seabees. This structure was specifically designed to utilize the construction expertise of the Seabees, who were tasked with demolition operations, reconnaissance, and other specialized tasks during amphibious landings in World War II.

The six-man team format allowed for a highly mobile and effective unit that could quickly adapt to different operational environments. Each member brought unique skills conducive to the mission, such as demolition, engineering, and underwater operations, leveraging the Seabees' training and experience in construction to fulfill their combat roles. This emphasis on small, specialized units provided the necessary agility and efficiency needed in combat scenarios, especially in the challenging and dynamic conditions of amphibious assaults.

In contrast, the other options reflect incorrect structures that do not align with the historical organization or mission of the NCDUs. The NCDUs were not made up of volunteers from the Marine Corps or from various naval branches, nor were they limited to smaller four-man or different team sizes that might undermine the operational capabilities developed within the six-man framework.