**Core Concept**
The question is testing the knowledge of chemotherapeutic agents used in transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). TACE is a procedure that involves delivering chemotherapy directly to the tumor through the hepatic artery, while also blocking the blood supply to the tumor using embolizing agents.

**Why the Correct Answer is Right**
The correct answer is **Mitomycin C**. Mitomycin C is a chemotherapeutic agent that is commonly used in TACE for HCC due to its ability to cross the blood-brain barrier and its efficacy against HCC cells. It works by inhibiting DNA synthesis and function, ultimately leading to cell death. Mitomycin C is often used in combination with other agents, such as doxorubicin, to enhance its efficacy.

**Why Each Wrong Option is Incorrect**
* **Option A:** Doxorubicin is a chemotherapeutic agent that is commonly used in TACE, but it is not the most commonly used agent. Doxorubicin works by intercalating DNA strands and inhibiting topoisomerase II, leading to cell death.
* **Option B:** Cisplatin is a chemotherapeutic agent that is commonly used in various types of cancer, but it is not typically used in TACE for HCC. Cisplatin works by cross-linking DNA strands and inhibiting DNA repair, leading to cell death.
* **Option D:** Irinotecan is a chemotherapeutic agent that is commonly used in colorectal cancer, but it is not typically used in TACE for HCC. Irinotecan works by inhibiting topoisomerase I, leading to DNA damage and cell death.

**Clinical Pearl / High-Yield Fact**
TACE is a treatment option for HCC that can provide local control of the tumor, while also improving symptoms and survival outcomes. The choice of chemotherapeutic agent used in TACE depends on various factors, including the patient's overall health, the size and location of the tumor, and the presence of liver function abnormalities.

**Correct Answer: C. Mitomycin C**