<prompt> Best assay for deficiency of von Willebamd factor is:Bleeding timeBT APTTBT APTT vWF-ristocetin factor assayPT  <response>: Answer is C BT APTT vWF-ristocetin factor assay Estimation of BT, APTT and VWF-Ristocetin factor assay would provide the maximal information to aid a diagnosis of VWF disease amongst the options provided 