The correct option is A Ammonia is less dense than air so it is collected by upward delivery.
Ammonia is less dense than air so it is collected by upward delivery or gas syringe method.
In upward delivery method a gas jar is connected by a tube to flask that is giving off gas. The gas that is less dense than air rises to the top of gas jar. The air in the gas jar is displaced until the gas jar is filled with collected gas. Ammonia is very soluble gas so the collection apparatus should be dry and not collected over water.