<prompt> 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 -Prothrombin timeClotting timePaial thromboplastin timePlatelet count  <response>: 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. 