## **Core Concept**
The pelvis is a complex structure that exhibits sexual dimorphism, with distinct differences between males and females. These differences are primarily related to childbearing and locomotion. The main differences lie in the size, shape, and structure of various pelvic components.

## **Why the Correct Answer is Right**
The correct answer, **C. Subpubic angle**, is a key differentiator between male and female pelvis. In females, the subpubic angle is wider (about 90 degrees) to facilitate childbirth, whereas in males, it is narrower (about 60 degrees). This angle is measured between the inferior pubic rami and is a critical factor in determining the pelvic outlet's size and shape.

## **Why Each Wrong Option is Incorrect**
* **Option A:** The greater sciatic notch is indeed different in males and females, but it is more related to the overall size and shape of the pelvis rather than a direct indicator of sex.
* **Option B:** The pre-auricular sulcus is a groove on the ilium that is more commonly found in females, but its presence or absence can vary and is not a definitive characteristic.
* **Option D:** The obturator foramen is larger in females, which contributes to a wider pelvic outlet, but like the greater sciatic notch, it's more about overall pelvic size and shape.

## **Clinical Pearl / High-Yield Fact**
A memorable point for exams is that the female pelvis has a wider **subpubic angle** (about 90 degrees) and a larger **pelvic outlet**, adaptations that facilitate childbirth. This contrasts with the male pelvis, which has a narrower subpubic angle (about 60 degrees) and is generally more robust for locomotion and muscle attachment.

## **Correct Answer:** C. Subpubic angle.