**Core Concept**
The eradication of congenital rubella syndrome (CRS) requires a targeted vaccination strategy to prevent rubella infection in susceptible individuals, particularly those at high risk of transmitting the virus to pregnant women. Rubella vaccination is most effective when administered to individuals who are least likely to be pregnant at the time of vaccination.

**Why the Correct Answer is Right**
The first priority group for rubella vaccination is young school-aged girls, typically between 9-14 years of age. This age group is chosen because they are least likely to be pregnant at the time of vaccination, thereby minimizing the risk of vaccine-induced rubella infection in pregnant women. Additionally, vaccinating young girls helps to prevent the spread of rubella among their peers, creating a "herd immunity" effect that protects vulnerable individuals, such as pregnant women and immunocompromised individuals.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because vaccinating young boys is not the primary target group for rubella vaccination. While boys can also benefit from rubella vaccination, the primary focus is on protecting young girls who are at higher risk of transmitting the virus to pregnant women.

**Clinical Pearl / High-Yield Fact**
Young girls should be vaccinated against rubella before they reach reproductive age to prevent congenital rubella syndrome in potential future offspring.

**Correct Answer:** C.