**Core Concept**
Nipple retraction is a clinical sign associated with breast carcinoma, resulting from the infiltration of cancer cells into the ducts or lobules of the breast. This process causes fibrosis and contraction of the surrounding tissue, leading to the retraction of the nipple.

**Why the Correct Answer is Right**
The correct answer is due to the infiltration of cancer cells into the ducts or lobules of the breast, leading to fibrosis and contraction of the surrounding tissue. This is a result of the malignant cells' ability to invade and destroy the normal tissue architecture, causing the nipple to become retracted. The involved ducts or lobules become fibrotic and contract, resulting in the characteristic nipple retraction.

**Why Each Wrong Option is Incorrect**
**Option A:** Traction from a skin lesion is not a common cause of nipple retraction in the context of breast carcinoma.
**Option B:** Edema from a lymphatic obstruction is not typically associated with nipple retraction in the context of breast carcinoma.
**Option C:** A skin infection is not a direct cause of nipple retraction in the context of breast carcinoma.

**Clinical Pearl / High-Yield Fact**
Nipple retraction is a classic clinical sign of breast carcinoma, often associated with a palpable mass or skin changes. It is essential to investigate any new or persistent nipple retraction in a woman over 40 years old.

**Correct Answer: C. Edema from lymphatic obstruction.**