**Core Concept**
Cord prolapse is a serious obstetric emergency where the umbilical cord slips through the cervix and into the birth canal before the baby, potentially causing fetal distress or death. This occurs when the presenting part of the fetus is not a head or an extended arm or leg, allowing the cord to pass through the cervix.

**Why the Correct Answer is Right**
The least chance of cord prolapse is seen in cases where the presenting part of the fetus is a head, as the head is the largest and most firm part of the fetus, effectively blocking the passage of the cord through the cervix. This is because the head is a fixed, rigid structure that will not allow the cord to pass through, thereby preventing cord prolapse.

**Why Each Wrong Option is Incorrect**
* **Option A:** - This option is incorrect as a footling breech presentation (where the feet are the presenting part) has a higher chance of cord prolapse due to the small and relatively loose feet allowing the cord to pass through the cervix.
* **Option B:** - This option is incorrect as a breech presentation (where the baby's buttocks are the presenting part) also has a higher chance of cord prolapse due to the relatively small and soft buttocks allowing the cord to pass through the cervix.
* **Option C:** - This option is incorrect as a transverse lie (where the baby is lying across the mother's abdomen) also has a higher chance of cord prolapse due to the baby's position allowing the cord to pass through the cervix.

**Clinical Pearl / High-Yield Fact**
A key factor in preventing cord prolapse is ensuring that the presenting part of the fetus is a head, which can be achieved through proper fetal positioning and uterine contraction.

**Correct Answer: D.**