## Core Concept
The question tests the understanding of urinary casts, which are cylindrical structures formed in the renal tubules and are indicative of various kidney conditions. They are classified based on their composition and appearance. Normally, a few hyaline casts may be present in the urine, but certain types of casts are associated with renal pathology.

## Why the Correct Answer is Right
Hyaline casts are composed of Tamm-Horsfall protein, which is a normal protein secreted by renal tubular cells. They are usually transparent and are considered a normal finding in urine, especially after exercise or dehydration. The presence of hyaline casts does not necessarily indicate kidney disease.

## Why Each Wrong Option is Incorrect
* **Option A:** Granular casts are abnormal and indicate renal disease. They are formed from the degeneration of cellular elements within the renal tubules.
* **Option B:** Red blood cell (RBC) casts are abnormal and suggest glomerulonephritis or other conditions that cause bleeding into the nephron.
* **Option D:** White blood cell (WBC) casts are indicative of pyelonephritis or other inflammatory conditions of the kidney.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the presence of hyaline casts in urine can be a normal finding, especially in concentrated urine or after intense physical activity. However, the presence of other types of casts, such as RBC, WBC, or granular casts, usually indicates renal pathology.

## Correct Answer: C. Hyaline cast