Which one of the following diseases presents as a swelling of either one or both parotid salivary glands, usually in children and young adults?

Mumps is a viral infection characterized by the swelling of the parotid salivary glands, which is a hallmark symptom of the disease. This condition is particularly prevalent among children and young adults, as it was more common before the widespread use of the MMR (measles, mumps, rubella) vaccine. The virus primarily affects the parotid glands, leading to noticeable swelling and discomfort, and it can also cause other systemic symptoms such as fever and fatigue.

In contrast, while measles, rubella, and tuberculosis can affect various body systems, they do not specifically cause the same type of swelling in the parotid glands. Measles presents with a distinct rash and respiratory symptoms, rubella also has a rash along with mild flu-like symptoms, and tuberculosis primarily affects the lungs, although it can impact other areas of the body in advanced cases. Therefore, mumps stands out as the disease specifically associated with the swelling of the salivary glands, making it the correct answer.