**Core Concept**
Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in young children, especially those under 2 years of age. It primarily affects the lungs and airways, leading to symptoms like cough, wheezing, and shortness of breath.

**Why the Correct Answer is Right**
RSV infection triggers a robust immune response, which includes the production of neutralizing antibodies and the activation of various immune cells. The virus targets the ciliated epithelial cells in the airways, leading to damage and inflammation. This results in the characteristic symptoms of RSV infection, such as bronchiolitis and pneumonia.

**Why Each Wrong Option is Incorrect**
**Option A:** RSV is indeed associated with **bronchiolitis**, a common lower respiratory tract infection in young children.
**Option B:** RSV is also linked to **pneumonia**, particularly in vulnerable populations like older adults and those with underlying health conditions.
**Option C:** RSV infection is not typically associated with **measles**; the two viruses have distinct epidemiological and clinical profiles.

**Clinical Pearl / High-Yield Fact**
RSV infection can be severe in premature infants and young children with underlying health conditions, such as heart disease or lung disease. Early recognition and treatment, including supportive care and antiviral therapy, are crucial in managing RSV-related complications.

**Correct Answer:** C. Measles