Ans. B. Venography* Duplex ultrasound is the initial investigation of choice in nearly all patients with suspected DVT.* Its reliability is dependent upon the skill of the user.* Major axial veins of the lower limb are well displayed.* It has a sensitivity of 98.7% and specificity of 100% for above-knee DVT and a sensitivity of 85.2% and specificity of 98.2% for below-knee DVT.* Gold standard/Best test for venous occlusion is invasive venography.