**Core Concept**
Meningoencephalitis is an inflammation of the brain and meninges, typically caused by viral infections. Enteroviruses are a group of viruses that commonly infect children and are known to cause a range of neurological symptoms.

**Why the Correct Answer is Right**
Enteroviruses, such as poliovirus, coxsackievirus, and echovirus, are highly contagious and can cause meningoencephalitis in children. The virus typically enters the body through the gastrointestinal tract and then spreads to the central nervous system (CNS), causing inflammation and damage to the brain and meninges. This can lead to symptoms such as fever, headache, stiff neck, and altered mental status.

**Why Each Wrong Option is Incorrect**
**Option A:** Mumps is a viral infection that primarily affects the salivary glands and can cause parotitis, but it is not a common cause of meningoencephalitis in children.

**Option B:** Arboviruses, such as West Nile virus and Eastern equine encephalitis virus, can cause meningoencephalitis, but they are more commonly associated with mosquito-borne transmission and are less common causes of the disease in children.

**Option C:** HSV (Herpes Simplex Virus) can cause encephalitis, but it is more commonly associated with adults and typically presents with a more severe and focal neurological syndrome.

**Clinical Pearl / High-Yield Fact**
Enterovirus meningoencephalitis is often associated with a mild prodrome of fever and gastrointestinal symptoms, followed by the onset of neurological symptoms. Early recognition and diagnosis are crucial, as antiviral therapy may be effective in reducing the severity of the disease.

**✓ Correct Answer: D. Enterovirus**