**Core Concept**
The uterosacral ligaments and the levator ani muscle play a crucial role in maintaining the anatomical integrity of the pelvic floor, thereby preventing uterine prolapse. The uterosacral ligaments provide support to the uterus by attaching it to the sacrum, while the levator ani muscle, part of the pelvic diaphragm, helps to maintain the pelvic floor's muscular tone.

**Why the Correct Answer is Right**
The broad ligament of the uterus is a fold of peritoneum that connects the uterus to the lateral walls of the pelvis. However, it does not provide significant support to the uterus, unlike the uterosacral ligaments and the levator ani muscle. In fact, the broad ligament can be a site for uterine prolapse, as it allows the uterus to herniate through the ligament. This is particularly seen in cases of uterine prolapse where the uterus descends into the vagina.

**Why Each Wrong Option is Incorrect**
**Option B:** The levator ani muscle is a key component of the pelvic floor, and its dysfunction can lead to pelvic organ prolapse, including uterine prolapse. Therefore, it is incorrect to say that the levator ani muscle prevents uterine prolapse.
**Option C:** The uterosacral ligaments provide crucial support to the uterus, and their integrity is essential in preventing uterine prolapse. Therefore, it is incorrect to say that the uterosacral ligaments do not prevent uterine prolapse.
**Option D:** The cardinal ligaments, including the uterosacral ligaments, play a vital role in maintaining the anatomical integrity of the cervix and the uterus. The transcervical ligament is not a recognized anatomical structure, but if it were, it would likely be involved in supporting the cervix and preventing prolapse.

**Clinical Pearl / High-Yield Fact**
The levator ani muscle is a key component of the pelvic floor, and its dysfunction can lead to pelvic organ prolapse. A weakened levator ani muscle can be a contributing factor to uterine prolapse, and its restoration is often a key component of surgical management.

**✓ Correct Answer: A. Broad ligament of uterus**