Choice A rationale:

Incubation is a characteristic clinical stage of measles infection. During the incubation period, which typically lasts 10 to 14 days, the person is infected with the measles virus, but there are no visible symptoms yet. The virus is actively replicating in the body, and the person is contagious during this stage.

Choice B rationale:

Convalescence is the stage during which the person begins to recover from the infection and the symptoms gradually improve. It is not a characteristic stage of measles infection.

Choice C rationale:

Resolution refers to the stage when the infection is completely cleared, and the symptoms have resolved. It is not specific to measles infection.

Choice D rationale:

Elimination is not a characteristic clinical stage of measles infection. It does not describe any specific phase of the disease progression.