## **Core Concept**
The subpubic angle, also known as the angle of the pubic arch, is an anatomical measurement used in obstetrics to assess the pelvic outlet. It is defined as the angle formed by the inferior pubic rami. This angle is crucial for determining the ease of childbirth.

## **Why the Correct Answer is Right**
The correct answer, **90-100 degrees**, represents the typical range for a normal subpubic angle. This range allows for a relatively easy passage of the fetal head during delivery. The angle is formed by the two inferior pubic rami and is an important factor in assessing the adequacy of the pelvic outlet for vaginal delivery.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Less than 90 degrees. A subpubic angle less than 90 degrees is considered narrow and may pose difficulties during childbirth, as it can impede the passage of the fetal head.
- **Option B:** More than 100 degrees. While a wider angle might not necessarily cause problems, an angle significantly greater than 100 degrees is not typically considered the norm for a subpubic angle.
- **Option D:** 60-80 degrees. This range is narrower than what is typically considered normal and could potentially cause issues during delivery.

## **Clinical Pearl / High-Yield Fact**
A subpubic angle within the normal range (90-100 degrees) is indicative of a favorable pelvic outlet for vaginal delivery. Obstetricians assess this angle, along with other pelvic measurements, to evaluate the feasibility of a vaginal delivery.

## **Correct Answer:** . 90-100 degrees