## **Core Concept**
Newborns have transplacentally acquired immunity, which means they receive antibodies from their mother through the placenta. This immunity provides protection against various infections. However, the effectiveness of this immunity varies depending on the disease.

## **Why the Correct Answer is Right**
The correct answer, **D. Poliomyelitis**, is right because while newborns can receive antibodies against poliomyelitis through breast milk and potentially through the placenta, the primary protection against poliomyelitis comes from vaccination. The transplacental transfer of antibodies against poliovirus does not provide long-lasting immunity, making it less effective compared to other diseases listed.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Newborns have transplacentally acquired immunity against **diphtheria** due to the transfer of antibodies from the mother. This provides them protection in early infancy.
- **Option B:** Similarly, **tetanus** antibodies are transferred from mother to child through the placenta, offering protection against neonatal tetanus.
- **Option C:** Newborns also acquire immunity against **pertussis** (whooping cough) through maternal antibodies, although this protection wanes over the first few months of life.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the transplacental immunity does not last a lifetime and wanes over time, typically within the first few months of life. This is why vaccination schedules start early in infancy, to build on the protection provided by maternal antibodies and to induce long-term immunity.

## **Correct Answer:** . **D. Poliomyelitis**