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: Pediatrics
A 10 year old boy presents with mucosal bleeding of 1 week duration. The investigation of choice that will be most useful in him is - 
Select and explain. 
A. Prothrombin time, B. Clotting time, C. Paial thromboplastin time, D. Platelet count
D: Platelet count
Answer: D: Platelet count 
Explanation: Ans. is 'd' i.e., Platelete count o Bleeding from mucosal surface suggests thrombocytopenia or defect in platelet function. o First do platelet count, if there is thrombocytopenia, fuher investigation will be required.