**Core Concept**
The measles virus is a highly contagious, enveloped RNA virus belonging to the genus Morbillivirus within the family Paramyxoviridae. It primarily targets the respiratory system, causing a severe, systemic infection.

**Why the Correct Answer is Right**
The measles virus attaches to the host cell via the hemagglutinin (H) protein, which binds to the CD46 receptor on the surface of immune cells. Following fusion of the viral envelope with the host cell membrane, the viral RNA is released into the cytoplasm, where it is transcribed and replicated. The measles virus then hijacks the host cell's machinery to produce new viral particles, which are released through a process of budding.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because the measles virus is not an example of a DNA virus.
**Option B:** This is incorrect because the measles virus is not typically associated with a latent infection state.
**Option C:** This is incorrect because the measles virus does not primarily target the gastrointestinal system.

**Clinical Pearl / High-Yield Fact**
Measles is a vaccine-preventable disease, and vaccination is recommended for all individuals who have not previously been infected or vaccinated. A single dose of the measles, mumps, and rubella (MMR) vaccine is approximately 93% effective in preventing measles.

**Correct Answer: D. Enveloped RNA virus.**