50 ml of 0.1 M KI forms a positive sol when mixed with

No. of millimoles of KI =5 ; No.of millimoles of AgNO3 must be greater than 5 to form a positive sol ;Number of millimoles of silver nitrate in options 1, 2 and 4 is 5, 5 and 4 respectively;In option 3, the number of millimoles of silver nitrate is 6 ;AgI is precipitated in presence of excess  AgNO3∴it forms Agl/Ag+It is +ve sol