1. Assume A, B, and C grant certain privileges on the Employee table to X, who in turn grants them to Y, as shown in the following table, with the numerical entries indicating the time of granting: Delete Insert 15 UserID X X Y X Table Grantor Employee A Employee B Employee x Employee C Read 15 20 25 30 25 20 25 30 At time t=35, B revokes all rights she previously granted to X. Which access rights of Y must be revoked and which may stay? Why