**Core Concept**
The lymphatic drainage of the vulva is a critical aspect of understanding the spread of vulvar cancer, particularly in the context of Ca Vulva. The vulva is a complex organ with multiple lymphatic drainage pathways, and knowledge of these pathways is essential for accurate staging and treatment planning.

**Why the Correct Answer is Right**
The anterior part of the vulva primarily drains to the inguinal lymph nodes due to its embryological origin from the labioscrotal swellings. The inguinal lymph nodes are located in the femoral triangle and are responsible for draining the lower limb, as well as the vulva. The lymphatic vessels from the anterior vulva traverse the superficial fascia of the perineum and enter the inguinal lymph nodes. This pathway is consistent with the lymphatic drainage of the lower limb and perineum. The inguinal lymph nodes are therefore the primary site for metastasis from the anterior part of the vulva.

**Why Each Wrong Option is Incorrect**
* **Option A:** The para-aortic lymph nodes are not a primary site for lymphatic drainage from the vulva. They are involved in the drainage of the upper genital tract, including the uterus, fallopian tubes, and ovaries.
* **Option C:** The obturator lymph nodes are not a primary site for lymphatic drainage from the vulva. They are involved in the drainage of the lower limb, but not the vulva.
* **Option D:** The femoral lymph nodes are not a primary site for lymphatic drainage from the vulva. They are involved in the drainage of the lower limb, but not the vulva.

**Clinical Pearl / High-Yield Fact**
The lymphatic drainage of the vulva is a critical aspect of vulvar cancer staging and treatment planning. The anterior part of the vulva primarily drains to the inguinal lymph nodes, while the posterior part drains to the deep inguinal and pelvic lymph nodes. Understanding these pathways is essential for accurate staging and treatment planning.

✓ Correct Answer: B. Inguinal