This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Most specific investigation in disseminated intravascular coagulation is - 
Select and explain. 
A. D - dimer assay, B. Bleeding time, C. Clotting time, D. Fibrinegen level
A: D - dimer assay
Answer: A: D - dimer assay 
Explanation: None