**Core Concept**
The question is testing the understanding of the anatomical pathway of lymphatic drainage for vulval carcinoma. In the context of vulval cancer, the lymphatic drainage is primarily to the inguinofemoral nodes. However, in cases of lower urethral involvement, the lymphatic drainage shifts to the internal iliac nodes, bypassing the inguinofemoral nodes.

**Why the Correct Answer is Right**
In vulval carcinoma, the lymphatic drainage is primarily to the inguinofemoral nodes. However, when the cancer involves the lower urethra, the lymphatic drainage shifts to the internal iliac nodes, as the lower urethra is closely related to the urethral sphincter and the urogenital diaphragm. The internal iliac nodes are located in the pelvis and receive lymphatic drainage from the lower urethra, thereby bypassing the inguinofemoral nodes. This is a critical concept in the management of vulval cancer, as it affects the choice of lymphadenectomy and the need for pelvic lymph node dissection.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the involvement of the lower urethra, which is the key factor in shifting the lymphatic drainage to the internal iliac nodes.
**Option B:** This option is incorrect because it implies that the lymphatic drainage remains in the inguinofemoral nodes even in the presence of lower urethral involvement, which is not the case.
**Option C:** This option is incorrect because it does not accurately describe the shift in lymphatic drainage in cases of lower urethral involvement of vulval carcinoma.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the involvement of the lower urethra is a critical factor in determining the lymphatic drainage pathway in vulval carcinoma. This knowledge helps in planning the appropriate surgical approach and in making accurate diagnoses.

**Correct Answer:** D