**Core Concept**
The pelvic outlet is a critical anatomical structure in the female pelvis, which is assessed during obstetric examinations to determine the potential for vaginal delivery. A contracted pelvic outlet can lead to complications during childbirth, such as obstructed labor.

**Why the Correct Answer is Right**
A contracted pelvic outlet is characterized by a reduced transverse diameter, which can be measured using various obstetric parameters. This reduction in diameter can be due to various factors, including bony deformities, soft tissue abnormalities, or postpartum changes. In a contracted pelvic outlet, the ischial tuberosities, ischial spines, and pubic arch are often more prominent, which can impede the passage of the fetal head during delivery.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the assessment of the pelvic outlet.
**Option B:** This option is incorrect because it refers to the pelvic inlet, which is the superior opening of the pelvis and is not directly related to the pelvic outlet.
**Option C:** This option is incorrect because it refers to the pelvic cavity, which is the entire space within the pelvis, rather than specifically the outlet.

**Clinical Pearl / High-Yield Fact**
A key point to remember when assessing the pelvic outlet is to consider the relationship between the ischial tuberosities, ischial spines, and pubic arch. A contracted pelvic outlet is often characterized by a more pronounced prominence of these structures, which can increase the risk of obstructed labor.

**Correct Answer: C. A contracted pelvic outlet is characterized by a reduced transverse diameter.**