The viral pathogen that frequently causes acute diarrhea in young children is:

The correct answer is choice B. A feeling of fullness in the ear.

Choice A rationale:

Nausea and vomiting are not typical symptoms of chronic otitis media with effusion (OME). OME involves fluid accumulation in the middle ear without signs of acute infection. It is commonly seen in children and may cause mild hearing impairment and a feeling of fullness in the ear.

Choice B rationale:

A feeling of fullness in the ear is a common symptom of OME. The fluid accumulation in the middle ear can lead to a sensation of pressure or fullness, as well as mild hearing loss. This can impact a child's ability to hear and communicate effectively.

Choice C rationale:

Severe pain in the ear is more characteristic of acute otitis media (AOM), which is an infection of the middle ear with signs of inflammation. In OME, pain is typically not a prominent symptom unless there is an underlying AOM episode.

Choice D rationale:

Fever as high as 40°C (104°F) is not a typical symptom of OME. OME is generally a chronic condition without acute signs of infection such as fever. However, if a fever is present, it might indicate a concurrent infection that needs further evaluation.

The correct answer is choice A, E.

Choice A rationale:

Using an air conditioner is an effective way to reduce exposure to pollens and dust. Air conditioners filter the air and help prevent outdoor allergens from entering the indoor environment. This choice is correct because it addresses one of the primary sources of exposure to allergens.

Choice B rationale:

Keeping humidity in the house above 60% is not a recommended approach. High humidity can promote the growth of mold and dust mites, which can exacerbate allergies. Maintaining humidity levels between 30-50% is generally recommended for reducing allergen exposure.

Choice C rationale:

Keeping pets outside might seem like a logical option to reduce allergen exposure; however, pet allergens can still be carried indoors on clothing and shoes. Moreover, if individuals are not allergic to pet dander, keeping the pets inside may not pose an issue.

Choice D rationale:

Replacing wall-to-wall carpeting with wood and tile floors is a good strategy for reducing allergen exposure. Carpets can trap dust, pollen, and other allergens, while hard surfaces are easier to clean and do not accumulate allergens as readily. This choice is correct because it addresses a common source of indoor allergens.

Choice E rationale:

Putting dust-proof covers on pillows and mattresses is another effective strategy for reducing allergen exposure. These covers create a barrier that prevents dust mites and their allergens from permeating the sleeping environment. This choice is correct because it directly addresses the issue of dust mite allergens.