**Core Concept**
Radical excision of previously irradiated tissue is associated with compromised vascularity and poor wound healing due to radiation-induced fibrosis and endothelial damage. In such cases, reconstructive surgeons rely on flaps with a robust vascular supply to ensure adequate perfusion and minimize the risk of flap failure.

**Why the Correct Answer is Right**
The correct answer is **C.** Pectoralis major myocutaneous flap. This flap is chosen due to its reliable blood supply from the thoracoacromial artery, which is less susceptible to radiation damage compared to the local vascular network. The pectoralis major muscle also provides a robust bulk of tissue, facilitating closure of the wound and reducing the risk of complications.

**Why Each Wrong Option is Incorrect**
* **Option A:** The radial forearm flap, although versatile, may not be the best choice in previously irradiated tissue due to its relatively thin skin paddle and potential for compromised perfusion.
* **Option B:** The latissimus dorsi flap is a good option for breast reconstruction but may not be the most suitable choice for cheek reconstruction, especially in irradiated tissue, due to its larger size and potential for donor site morbidity.
* **Option D:** The gastroepiploic artery flap is not a commonly used flap in head and neck reconstruction, and its use in previously irradiated tissue may be associated with a higher risk of complications.

**Clinical Pearl / High-Yield Fact**
When planning reconstruction in previously irradiated tissue, it's essential to select flaps with a robust vascular supply and a proven track record in such cases. The pectoralis major myocutaneous flap is a reliable option, but other flaps, such as the scapular or parascapular flaps, may also be considered in experienced hands.

**Correct Answer: C. Pectoralis major myocutaneous flap.**