**Core Concept**

Intravenous pyelography (IVP) is a diagnostic imaging technique used to visualize the renal pelvis, ureters, and kidneys, assessing their function and structure. During an IVP, a contrast agent is injected into the bloodstream, allowing the kidneys to be visualized on X-rays. A contracted kidney indicates impaired functioning or structural abnormalities.

**Why the Correct Answer is Right:**

The correct answer represents a clinical scenario where a contracted kidney is observed during intravenous pyelography. In this case, Option C ("Obstructed kidney") is the correct answer as it reflects the situation where the kidney is contracted due to obstruction of urine flow. This could be caused by various factors such as ureteral stones, strictures, tumors, or other structural abnormalities.

**Why Each Wrong Option is Incorrect:**

Option A ("Hypertensive kidney") refers to an enlarged kidney due to hypertension, which is a different scenario from a contracted kidney caused by obstruction.

Option B ("Renal atrophy") is related to the reduction of kidney size due to loss of nephrons, not necessarily involving obstruction.

Option D ("Glomerular disease") is a general term for kidney diseases affecting the glomeruli, but it does not specifically explain the contracted kidney observed in IVP.

**Why Option C is Right:**

In a contracted kidney due to obstruction, the kidney becomes smaller due to the reduced filtration of blood and impaired excretion of waste products. This leads to atrophy and potentially further complications like hydronephrosis and infection.

**Clinical Pearl:**

A contracted kidney on IVP should prompt further investigations to identify the cause, such as imaging studies (CT scan, ultrasound) and clinical evaluation (vital signs, blood tests) to manage the underlying condition and restore kidney function.

**Correct Answer:** C. Obstructed kidney