What distinguishes NCDUs from UDTs?

The distinguishing feature of NCDUs (Naval Combat Demolition Units) compared to UDTs (Underwater Demolition Teams) is their specialized focus on clearing landing beaches, which is reflected in the correct answer.

NCDUs were specifically created to support amphibious assaults during World War II by ensuring that obstacles in the water and on the beach were cleared for incoming forces. They were trained to demolish structures such as enemy defenses and mines that posed a threat to landing troops. This focused mission set them apart from UDTs, which were also involved in similar operations but had a broader range of underwater demolition tasks, including reconnaissance and beach surveys.

While other options touch on aspects of NCDUs or UDTs, they do not accurately capture their primary distinction. For example, NCDUs were not strictly land forces, nor were they predominantly responsible for logistics and supply, as these functions typically fall outside the specific combat and demolition focus of the units. Recognizing this unique role of NCDUs in beach clearing emphasizes their importance in successful amphibious operations.