**Core Concept**
The question is testing the ability to identify conditions where a head of breech presentation will have difficulty in delivery. This requires knowledge of obstetric anatomy and fetal positioning. The head of a breech baby presents in the birth canal in a downward position, which can make delivery challenging in certain conditions.

**Why the Correct Answer is Right**
The correct answer is a condition where the head of a breech baby can be easily delivered vaginally. In a normal pelvis, the head of a breech baby can pass through the pelvic inlet, mid-pelvis, and outlet with ease. However, certain conditions such as **pelvic contraction** can make delivery more difficult. In a normal pelvis, the head of a breech baby can be delivered vaginally without any complications.

**Why Each Wrong Option is Incorrect**
* **Option A:** **Pelvic contraction** would make delivery more difficult, as the head of a breech baby would have to navigate through a smaller pelvic inlet, mid-pelvis, and outlet.
* **Option B:** **Congenital hip dislocation** would make delivery more difficult, as the abnormal hip joint would affect the rotation of the baby's head and body during delivery.
* **Option C:** **Cephalopelvic disproportion (CPD)** would make delivery more difficult, as the baby's head would be too large to pass through the mother's pelvis.

**Clinical Pearl / High-Yield Fact**
When a breech baby is presenting head-first, the risk of umbilical cord prolapse and fetal distress is higher. Therefore, immediate delivery is often recommended in such cases.

**Correct Answer: D. Normal pelvis.**