Spontaneous bleeding usually occurs when the platelet counts fall below

Ans. (a) 20000/uL(Ref: Robbins 9th/pg 662; 8th/pg 692)In general, the risk of significant spontaneous hemorrhage increases gradually as the platelet count drops to <50x109/L and is high at counts <5x109/L. So among the options the best answer is 10,000/ul.