Correct option: Medium (moderate) risk.
Step 1: Apply the original Wells PE criteria. Clinical signs of DVT score 3 points and tachycardia (heart rate > 100) scores 1.5 points. The active malignancy also adds 1 point.
Step 2: The three-tier original Wells cut-offs are: low < 2.0, moderate 2.0 to 6.0, and high > 6.0. The score here sits well inside the 2.0 to 6.0 band, placing the patient in the moderate (medium) risk group.
Why not the others: The score does not reach > 6.0, so it is not high, and it is clearly above 2.0, so it is not low. D-dimer is not part of the Wells score itself, so option D is wrong; D-dimer is used after risk stratification, not to compute it.
Ref: Bailey and Love, Short Practice of Surgery, 27th edition, 2018.