**Core Concept**
Hepatitis A virus (HAV) is a pathogen that causes an acute, self-limiting infection of the liver. It is primarily transmitted through the fecal-oral route, often via contaminated food or water.

**Why the Correct Answer is Right**
HAV infection typically affects children and young adults, with the highest incidence rates observed in individuals under the age of 15. This is because HAV is highly contagious and often spreads in households, schools, and communities. The virus is usually transmitted through fecally contaminated food or water, which can occur more frequently in settings where hygiene practices are inadequate.

**Why Each Wrong Option is Incorrect**

**Option A:**
This option is incorrect because Hepatitis A virus primarily affects children and young adults, rather than the elderly population.

**Option B:**
This option is incorrect because Hepatitis C virus (HCV) is a different pathogen that causes a chronic infection, often transmitted through blood-to-blood contact.

**Option C:**
This option is incorrect because Hepatitis B virus (HBV) can affect individuals of all ages, but it is more commonly transmitted vertically from mother to child or through blood-to-blood contact.

**Option D:**
This option is incorrect because Hepatitis E virus (HEV) is also transmitted through the fecal-oral route, but it is more commonly associated with outbreaks in developing countries and affects a broader age range.

**Clinical Pearl / High-Yield Fact**
Hepatitis A virus infection is typically self-limiting and resolves on its own within 2-6 months, but vaccination is recommended for individuals at high risk of exposure, such as travelers to endemic areas or individuals with underlying liver disease.

**Correct Answer:** D.