**Core Concept**
Hepatitis A virus (HAV) is a non-enveloped, positive-sense RNA virus that primarily causes acute hepatitis. It is transmitted via the fecal-oral route, often through contaminated food or water.

**Why the Correct Answer is Right**
HAV infection is characterized by the replication of the virus in the liver, leading to inflammation and liver damage. The virus enters the host through the oral route, where it is taken up by enterocytes and subsequently released into the bloodstream. The virus then targets hepatocytes, where it replicates and causes liver damage. The immune response to HAV infection is primarily cell-mediated, with T lymphocytes playing a crucial role in clearing the virus.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because HAV does not have an envelope, unlike some other viruses such as hepatitis B virus (HBV) and hepatitis C virus (HCV).
**Option B:** This option is incorrect because HAV is not transmitted through the parenteral route, unlike HBV and HCV, which can be transmitted through blood and other bodily fluids.
**Option C:** This option is incorrect because HAV does not have a significant impact on the liver's ability to regenerate, unlike other forms of hepatitis such as chronic hepatitis B and C.

**Clinical Pearl / High-Yield Fact**
HAV infection is typically self-limiting and does not lead to chronic hepatitis or liver cirrhosis. However, it can cause significant morbidity, particularly in individuals with underlying liver disease or those who are malnourished.

**Correct Answer: D.**