A 38-year-old woman with a 15-year history of migraine with aura presents to the emergency department with acute-onset left leg swelling, calf pain, and warmth that began this morning. She initiated smoking 3 months ago and has been on combined oral contraceptives for 2 years. Vital signs are stable with BP 128/82, HR 92, RR 16, temp 37.2°C, and SpO2 98% on room air. Physical examination reveals unilateral lower extremity edema with palpable warmth over the calf. Compression ultrasonography demonstrates absence of compressibility in the left popliteal vein with echogenic thrombus. D-dimer is elevated at 2.8 μg/mL. Chest examination is unremarkable and pulse oximetry remains normal. Which of the following is the primary modifiable risk factor contributing to her venous thromboembolism?

1. A)Migraine with aura, which causes recurrent transient hypercoagulability through platelet activation
2. B)Combined oral contraceptive use, which increases risk through estrogen-mediated changes in coagulation factorsGABARITO
3. C)Smoking within 3 months of presentation, which impairs endothelial function and platelet adhesion
4. D)Recent immobilization from prolonged sitting related to work or travel during thrombosis development
5. E)Underlying inherited thrombophilia such as Factor V Leiden, which is unmasked by oral contraceptive use