**Core Concept**
Complete duplication of the ureters is a rare congenital anomaly where both the upper and lower poles of the kidney are duplicated, resulting in two separate ureters for each kidney. This anomaly can be classified into several types based on the degree of duplication, with complete duplication being the most severe form.

**Why the Correct Answer is Right**
In complete duplication of the ureters, the proximal segment is typically the ectopic ureter, which originates from the upper pole of the kidney and does not insert into the bladder. Instead, it inserts into the urethra or other adjacent structures. This is because the ureteric bud fails to properly differentiate and canalize, leading to the formation of a separate, non-functioning ureteric system.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as the distal segment is typically the ectopic ureter in complete duplication, not the proximal segment.
* **Option B:** This option is incorrect as the ureteric bud does not form a separate ureteric system in complete duplication, but rather a non-functioning ureteric system.
* **Option C:** This option is incorrect as the ectopic ureter is typically the non-functioning ureter, not the functioning ureter.

**Clinical Pearl / High-Yield Fact**
It's essential to note that complete duplication of the ureters is often associated with other urinary tract anomalies, such as vesicoureteral reflux and renal ectopia. A thorough imaging evaluation is necessary to diagnose and manage this condition.

**Correct Answer:** A.