**Core Concept**
Acute non-suppurative sialadenitis refers to an inflammatory condition of the salivary glands, characterized by the absence of pus formation. This condition is often precipitated by various factors, including viral infections, dehydration, and certain medications.

**Why the Correct Answer is Right**
Acute non-suppurative sialadenitis is commonly associated with mumps virus infection. The mumps virus targets the salivary glands, particularly the parotids, leading to inflammation and swelling. The viral infection triggers an immune response, resulting in the production of cytokines and chemokines that exacerbate the inflammatory process.

**Why Each Wrong Option is Incorrect**
**Option A:** While dehydration can contribute to sialadenitis, it is not the primary cause of acute non-suppurative sialadenitis.

**Option B:** Certain medications can cause sialadenitis, but they are more likely to cause suppurative or chronic forms of the condition.

**Option C:** While viral infections can cause sialadenitis, mumps virus is the most common and well-documented cause of acute non-suppurative sialadenitis.

**Clinical Pearl / High-Yield Fact**
Mumps virus infection can lead to complications such as orchitis, oophoritis, and meningitis in some cases. The mumps vaccine is effective in preventing these complications and is recommended as part of routine childhood vaccination schedules.

**Correct Answer: C. Mumps virus infection.**