**Core Concept**
The perirenal fascia, also known as Gerota's fascia, is a layer of connective tissue that surrounds the kidney and its associated structures. To attach the perirenal fascia to the peritoneum, a specific layer of fascia is required to bridge the two.

**Why the Correct Answer is Right**
The correct answer is the transversalis fascia, which is a layer of fascia that lies between the transversus abdominis muscle and the extraperitoneal fascia. The transversalis fascia serves as a bridge between the perirenal fascia and the peritoneum, allowing for the attachment of the perirenal fascia to the peritoneum. This attachment is crucial for the proper positioning and mobility of the kidney.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the attachment of the perirenal fascia to the peritoneum.
**Option B:** This option is incorrect because the renal fascia is not directly attached to the peritoneum through this fascial layer.
**Option C:** This option is incorrect because the parietal peritoneum is not directly attached to the perirenal fascia through this fascial layer.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the transversalis fascia serves as a bridge between the perirenal fascia and the peritoneum, allowing for the proper attachment and positioning of the kidney.

**Correct Answer: C. Transversalis fascia**