**Core Concept**
The collecting part of the kidney, also known as the collecting system, is responsible for the transport of urine from the renal pyramids to the renal pelvis and ultimately to the ureters. This system plays a crucial role in the excretion of waste products from the body.

**Why the Correct Answer is Right**
The correct answer is related to the embryological development of the kidney. The collecting system of the kidney is derived from the ureteric bud, a precursor structure that gives rise to the collecting ducts, calyces, and ureters. During embryonic development, the metanephric mesenchyme differentiates into the renal cortex, while the ureteric bud grows into the renal parenchyma, forming the collecting system.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately represent the embryological origin of the collecting system.
**Option B:** This option is also incorrect as it does not correctly describe the development of the collecting system.
**Option C:** This option is incorrect as it is a component of the kidney but not the origin of the collecting system.

**Clinical Pearl / High-Yield Fact**
The collecting system of the kidney is composed of the calyces, renal pelvis, and ureters, which are all derived from the ureteric bud. This knowledge is essential for understanding renal anatomy and pathophysiology.

**Correct Answer:** D.