**Core Concept**
The sacrotuberous ligament is a strong ligament in the posterior pelvis that connects the sacrum to the ischial tuberosity. It plays a crucial role in stabilizing the sacroiliac joint and maintaining pelvic integrity.

**Why the Correct Answer is Right**
The sacrotuberous ligament is pierced by the short filaments of the posterior sacroiliac ligament, but more importantly, it is pierced by the _sacrotuberous nerve_ (also known as the _piriformis nerve_), a branch of the sacral plexus. This nerve runs through the sacrotuberous ligament to supply the gluteus maximus muscle and the skin overlying the gluteal region.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the sacrotuberous ligament is not pierced by the superior gluteal nerve, which primarily supplies the gluteus medius and minimus muscles.

**Option B:** This option is incorrect as the inferior gluteal nerve, which supplies the gluteus maximus muscle, does not pierce the sacrotuberous ligament.

**Option C:** This option is incorrect as the pudendal nerve, which supplies the external genitalia and the perineal muscles, does not pierce the sacrotuberous ligament.

**Clinical Pearl / High-Yield Fact**
The sacrotuberous ligament is also a common site for the insertion of the piriformis muscle, which can lead to sciatic nerve compression and piriformis syndrome.

**Correct Answer: B. Inferior Gluteal Nerve.**