What are the three aerial delivery methods used in large-scale combat operations?

In large-scale combat operations, the three primary aerial delivery methods are airdrop, airland, and sling load.

Airdrop involves the deployment of cargo or personnel from an aircraft during flight, allowing for rapid resupply or troop insertion in areas that may be difficult to access via ground routes. This method is particularly valuable when aiming to reach remote or contested zones swiftly.

Airland refers to the transportation of cargo or personnel by aircraft with a landing operation at a designated airfield or landing zone. This method allows for heavy and bulky items to be delivered close to the battlefield in a more controlled environment, facilitating logistics and support to ground forces.

Sling load is the technique of transporting cargo attached to an external hook on a helicopter. This capability allows for the movement of items that are too heavy or cumbersome to transport internally, thus enabling flexibility in logistics and support operations during combat.

The other answer choices incorporate elements that don't fit into the established methods used for aerial delivery in large-scale operations. For instance, including "helicopter" alone does not specify how it is utilized in aerial delivery, while options referencing ground transportation do not pertain to aerial methods at all, which are critical for rapid response in combat scenarios.