**Core Concept**
Hepatitis A virus (HAV) is a non-enveloped, single-stranded RNA virus belonging to the Picornaviridae family, primarily transmitted through the fecal-oral route. It causes acute hepatitis, which is self-limiting in most cases but can lead to severe liver disease in vulnerable populations.

**Why the Correct Answer is Right**
HAV enters the body through contaminated food or water, replicating in the gastrointestinal tract before spreading to the liver via the bloodstream. The virus triggers an immune response, leading to the release of pro-inflammatory cytokines and the activation of hepatic immune cells, resulting in liver injury and inflammation. The liver's regenerative capacity typically allows for recovery from the infection.

**Why Each Wrong Option is Incorrect**
* **Option A:** HAV is not an enveloped virus; it lacks a lipid envelope surrounding its capsid.
* **Option B:** HAV is primarily transmitted via the fecal-oral route, not through blood transfusions or sexual contact.
* **Option C:** HAV does not have a DNA genome; it is a single-stranded RNA virus.

**Clinical Pearl / High-Yield Fact**
HAV vaccination is recommended for individuals traveling to high-risk areas, such as developing countries with poor sanitation, and for those with underlying liver disease or immunocompromised conditions.

**Correct Answer: B. Hepatitis A virus is primarily transmitted via the fecal-oral route.**