## Core Concept
The transmission of HIV from an infected mother to her infant can occur during pregnancy, childbirth (also known as perinatal transmission), or through breastfeeding. This transmission is influenced by several factors, including the mother's viral load, the mode of delivery, and whether the infant is breastfed.

## Why the Correct Answer is Right
The correct answer involves understanding the periods and modes through which HIV can be transmitted from mother to child.
- **During Pregnancy:** HIV can cross the placenta, leading to infection of the fetus.
- **During Childbirth:** The baby is exposed to the virus in the mother's blood and vaginal secretions, which can occur during a vaginal delivery.
- **Through Breastfeeding:** HIV-infected mothers can transmit the virus to their infants through breast milk.

## Why Each Wrong Option is Incorrect
Since the question and specific options (A, B, C, D) are not provided, a general approach to evaluating incorrect options regarding mother-to-child transmission of HIV is as follows:
- **Option A:** If this option suggests a false mode of transmission (e.g., casual contact), it is incorrect because HIV is not transmitted through casual contact like hugging, sharing food, or mosquito bites.
- **Option B:** If this option denies a known mode of transmission (e.g., during pregnancy), it is incorrect because HIV can indeed be transmitted from mother to child during pregnancy.
- **Option C:** If this option inaccurately describes the risk or method of prevention (e.g., suggesting that HIV transmission can be completely prevented by elective cesarean delivery alone), it might be incorrect because while elective cesarean delivery before the onset of labor and before the rupture of membranes can reduce the risk of mother-to-child transmission, it is not the sole preventive measure.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **antiretroviral therapy (ART)** significantly reduces the risk of mother-to-child transmission of HIV. ART is recommended for all pregnant women living with HIV to control their viral load and prevent transmission to their infants. Additionally, **neonatal antiretroviral prophylaxis** is given to the newborn to further reduce the risk of HIV infection.

## Correct Answer: D.