**Core Concept**
The World Health Organization (WHO) has launched various campaigns and initiatives to address global health concerns. The slogan of a particular year is often a reflection of the organization's focus on a specific health issue. In this case, the correct answer is related to reproductive and child health, which is a critical area of focus for the WHO.

**Why the Correct Answer is Right**
The correct answer is "Maternal and child health." This is because the WHO has consistently emphasized the importance of maternal and child health as a priority area. In 2005, the WHO launched a campaign to reduce maternal and child mortality, which is a major public health concern globally. The campaign aimed to improve access to healthcare services, particularly for pregnant women and children under the age of five. This is in line with the WHO's vision of achieving universal health coverage and improving health outcomes for all populations.

**Why Each Wrong Option is Incorrect**
**Option A:** Road safety is an important public health issue, but it was not the focus of the WHO's campaign in 2005.

**Option C:** Aging is a significant health concern, particularly in developed countries, but it was not the primary focus of the WHO's campaign in 2005.

**Option D:** Physical activity is an important aspect of public health, but it was not the main focus of the WHO's campaign in 2005.

**Clinical Pearl / High-Yield Fact**
The WHO's focus on maternal and child health is reflected in the Millennium Development Goals (MDGs), which included targets to reduce maternal and child mortality. This highlights the importance of reproductive and child health as a global health priority.

**Correct Answer Line**
✓ Correct Answer: B. Maternal and child health