**Core Concept**
The patient in this scenario has sustained a traumatic injury to the inguinal region, resulting in a transected common femoral vein. This type of injury is a classic example of a vascular trauma, which requires prompt and appropriate management to prevent complications such as bleeding, thrombosis, and limb ischemia.

**Why the Correct Answer is Right**
Given the transection of the common femoral vein, the treatment of choice is a venous repair or reconstruction. This is because the common femoral vein plays a crucial role in venous return from the lower limb, and its transection can lead to significant swelling, pain, and potential complications. The presence of distal pulsation in the patient's limb suggests that the arterial circulation is intact, and therefore, the primary focus should be on repairing the venous injury. The normal examination of the internal iliac, common iliac, and external femoral artery further supports the need for a venous repair.

**Why Each Wrong Option is Incorrect**
**Option A:** Applying a tourniquet would be incorrect because it would compromise the arterial circulation to the limb, potentially leading to ischemia and further complications.
**Option B:** Administering anticoagulants would be incorrect because the primary issue is a physical transection of the vein, not a thrombotic event.
**Option C:** Performing a fasciotomy would be incorrect because it is not necessary in this scenario, and would not address the underlying venous injury.

**Clinical Pearl / High-Yield Fact**
In cases of vascular trauma, it is essential to prioritize the repair of the injured vessel to prevent complications such as bleeding, thrombosis, and limb ischemia. A thorough understanding of the anatomy and physiology of the vascular system is critical in making accurate diagnoses and implementing effective treatment strategies.

**Correct Answer:** D.