**Core Concept:** Embolization is a minimally invasive medical procedure used to obstruct blood flow to a specific organ or vessel by blocking the blood vessel with a particulate material. Embolization agents are designed to selectively target and occlude blood vessels while minimizing damage to surrounding tissues.

**Why the Correct Answer is Right:**

Correct Answer: C. AngioJet (Possesses a high-velocity jet of contrast medium and saline to create a hypertonic solution that causes thrombosis)

AngioJet is a specific embolization agent designed to occlude blood vessels. It works by creating a high-velocity jet of contrast medium and saline, which generates a hypertonic solution. This hypertonic solution causes vasoconstriction, platelet aggregation, and subsequent thrombosis, effectively obstructing blood flow to the targeted vessel without causing significant damage to surrounding tissues.

**Why Each Wrong Option is Incorrect:**

A. Gelfoam (It is a sponge-like substance made from porcine collagen that absorbs blood and forms a fibrin clot, effectively occluding blood flow) - While Gelfoam is a type of embolization agent, it does not generate a hypertonic solution like AngioJet. Instead, it absorbs blood and forms a fibrin clot, blocking blood flow.

B. Ethanol (Ethanol is a liquid embolization agent that selectively destroys blood vessels by damaging endothelial cells and causing vasoconstriction. It is not used for selective vascular occlusion.) - Ethanol is an alcohol that can selectively destroy blood vessels by damaging endothelial cells and causing vasoconstriction. However, it is not specifically designed for selective vascular occlusion like AngioJet.

D. Stent-Grafts (Stent-grafts are devices used to reinforce an aneurysm sac and prevent its rupture, not for occluding blood vessels.) - Stent-grafts are used to reinforce aneurysms and prevent their rupture, not for occluding blood vessels like AngioJet.

**Clinical Pearl:** AngioJet is an effective embolization agent for selective vascular occlusion due to its unique mechanism of creating a hypertonic solution that induces thrombosis, minimizing damage to surrounding tissues. Gelfoam, ethanol, and stent-grafts are not specifically designed for selective vascular occlusion but have other indications and mechanisms, such as destroying blood vessels, causing vasoconstriction, or reinforcing aneurysms.