**Core Concept**
The measles virus is a highly contagious and serious viral infection that primarily affects the respiratory system, causing fever, cough, runny nose, and a characteristic rash. It is a member of the Paramyxoviridae family and is spread through respiratory droplets.

**Why the Correct Answer is Right**
The measles virus belongs to the genus Morbillivirus, which is characterized by its single-stranded RNA genome and enveloped structure. It attaches to the host cells via the hemagglutinin (H) protein, which binds to the CD46 receptor on the surface of immune cells. This interaction triggers the fusion of the virus with the host cell membrane, allowing the viral genome to be released into the cell.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not accurately describe the measles virus.
**Option B:** Incorrect because it is a different type of virus that causes a different disease.
**Option C:** Incorrect because it is a different genus within the same family, but not the correct one for measles.

**Clinical Pearl / High-Yield Fact**
The measles virus is highly contagious and can cause serious complications, such as pneumonia, encephalitis, and death, especially in young children and individuals with weakened immune systems.

**Correct Answer: C. A member of the genus Morbillivirus.**