All Navy ships can be classified as which of the following?

The correct classification for all Navy ships is that they fall into two main categories: combatant and auxiliary. Combatant ships are those that are designed primarily for warfare and have the capabilities to engage in battle. This includes vessels such as aircraft carriers, destroyers, and submarines. On the other hand, auxiliary ships support combatant ships by providing logistical support, transport, repair, and other services necessary for effective naval operations. This classification is essential for understanding the roles and functions of different types of ships within the Navy.

The other options presented do not encompass the full spectrum of naval vessels. "Cadet, auxiliary" does not apply as 'cadet' is not a classification for ships but rather refers to training personnel. "Cruiser, destroyer" are specific types of combatant ships and do not account for the auxiliary vessels that are also part of the Navy's structure. Lastly, "merchant, combatant" mixes civilian and military classifications, while Navy ships exclusively fall into the combatant or auxiliary categories. Hence, the most comprehensive and accurate classification is combatant and auxiliary.