## Core Concept
The ureters are muscular tubes that carry urine from the kidneys to the urinary bladder. During surgical procedures, it is crucial to identify and preserve the ureters to prevent damage and potential complications. Ureters can be identified through their anatomical location and specific characteristics.

## Why the Correct Answer is Right
The correct answer, **peristalsis**, is a key feature for identifying ureters during surgery. Ureters exhibit peristalsis, which are rhythmic, wave-like muscle contractions that help propel urine from the kidneys to the bladder. This characteristic movement is a reliable way to distinguish ureters from other structures.

## Why Each Wrong Option is Incorrect
* **Option A:** The statement is missing, but typically, ureters are not primarily identified by their color.
* **Option B:** While the ureters do have a specific location and course through the retroperitoneum, their location alone without other identifying features might not be sufficient for identification during surgery.
* **Option C:** The statement is missing, but other than peristalsis, another method could involve the use of ureteral catheters or dyes, but these are not listed.

## Clinical Pearl / High-Yield Fact
A useful clinical pearl for identifying ureters during surgery is to look for their peristalsis. This can be enhanced by gently stimulating the ureter or by using a small amount of fluid. Recognizing the ureters is critical to prevent iatrogenic injury, which can lead to serious complications such as fistulae or obstruction.

## Correct Answer: D. peristalsis.