Which of the following conditions is characterized by eardrum inflammation?

The condition characterized by eardrum inflammation is otitis media. This is an infection or inflammation of the middle ear, which often involves the eardrum as well. In otitis media, fluid builds up in the middle ear, which can cause pain and may lead to the eardrum becoming red or bulging due to inflammation. This condition is common, especially in young children, and is frequently a result of upper respiratory infections or allergies that cause blocked Eustachian tubes.

The other conditions listed do not specifically involve the eardrum or middle ear structure. Sinusitis refers to inflammation of the sinus cavities, pneumonia is an infection of the lungs, and bronchitis involves inflammation of the bronchial tubes in the lungs. Therefore, none of these conditions is directly linked to the inflammation of the eardrum.