**Core Concept**
Nipple retraction in breast cancer is a clinical sign resulting from the infiltration of cancer cells into the lactiferous ducts. The lactiferous ducts are a crucial part of the mammary gland, responsible for milk ejection during lactation. Infiltration of cancer cells into these ducts can lead to the destruction of tissue, causing the nipple to retract.

**Why the Correct Answer is Right**
The correct answer is B. Lactiferous ducts, as cancer cells infiltrating these ducts can disrupt the normal architecture of the breast tissue, leading to nipple retraction. This occurs due to the destruction of the ductal epithelium and the subsequent contraction of the surrounding tissue, causing the nipple to pull inward. The lactiferous ducts are a common site for breast cancer metastasis, and their infiltration is a critical factor in the development of nipple retraction.

**Why Each Wrong Option is Incorrect**
**Option A:** Suspensory ligaments are not directly involved in the process of nipple retraction in breast cancer. While they do provide support to the breast, their infiltration is not a primary cause of nipple retraction.

**Option C:** Lymphatic infiltration can lead to lymphedema and other complications, but it is not the primary cause of nipple retraction in breast cancer.

**Option D:** Pectoralis fascia is a layer of connective tissue that surrounds the pectoralis muscle, and its infiltration is not directly related to nipple retraction in breast cancer.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that nipple retraction is a significant clinical sign in breast cancer, often indicating advanced disease. A thorough examination, including a detailed history and physical examination, is crucial in identifying this sign and guiding further diagnostic and therapeutic interventions.

✓ Correct Answer: B. Lactiferous ducts.