**Core Concept**
The kidney cortex is the outermost layer of the kidney, playing a crucial role in filtering waste products from the blood and regulating various electrolytes and fluids. It is primarily composed of renal corpuscles (glomeruli and Bowman's capsules) and the proximal and distal convoluted tubules, which are involved in the reabsorption and secretion of substances.

**Why the Correct Answer is Right**
The collecting tubule and duct are indeed located in the kidney cortex, and they are responsible for the final concentration of urine. The collecting tubules are short, blind-ended structures that receive fluid from the distal convoluted tubules and merge into larger collecting ducts. These ducts then empty into the renal calyces, which are cup-shaped structures that collect and channel urine into the renal pelvis. The collecting tubules and ducts are crucial for regulating electrolyte balance and water reabsorption in the kidneys.

**Why Each Wrong Option is Incorrect**
**Option A:** The Loop of Henle is a U-shaped structure located in the renal medulla, which helps to concentrate the urine by creating a concentration gradient in the medulla. It is not found in the kidney cortex.
**Option B:** The pyramids are also located in the renal medulla and are composed of the straight portions of the distal convoluted tubules and the collecting ducts. They are not found in the kidney cortex.
**Option D:** The calyces are cup-shaped structures that collect and channel urine from the collecting ducts into the renal pelvis. While they are involved in the urine collection process, they are not located in the kidney cortex.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the kidney cortex is primarily composed of the renal corpuscles and the proximal and distal convoluted tubules, which are responsible for the initial filtration and reabsorption of substances. The collecting tubules and ducts, on the other hand, are located in the renal medulla and are involved in the final concentration of urine.

✓ Correct Answer: C. Collecting tubule and duct