## **Core Concept**
The question pertains to the anatomical classification of pelvis types, specifically focusing on the characteristics of the pelvic ala. The pelvis can be categorized into different types based on the shape and size of its inlet and the structure of the pelvic ala.

## **Why the Correct Answer is Right**
The correct answer, **D. Triradiate pelvis**, is associated with a single pelvic ala. In a triradiate pelvis, there is a characteristic fusion of the pubic bones, leading to the appearance of a single ala on one side. This type of pelvis is a result of a developmental anomaly.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not describe a known classification related to a single pelvic ala.
- **Option B:** Similarly, this option does not correspond with the anatomical feature in question.
- **Option C:** This option also does not relate to the characteristic of having a single pelvic ala.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that variations in pelvic anatomy can significantly impact childbirth and surgical procedures. Understanding these variations is crucial for obstetricians and surgeons.

## **Correct Answer:** **D. Triradiate pelvis**