Please explain well

1. The following SQL statement: UPDATE R SET a = 10 WHERE b IN (SELECT c FROM S) ANI NOT EXISTS (SELECT * FROM T WHERE T. a = R. a); requires certain privileges to execute. Determine all the privileges required, and then indicate which of the following privileges is not useful in allowing the above statement to be executed. To be precise, say a privilege P is useful if there is some set of other privileges such that the statement cannot be executed with just those privileges, but if we add privilege P, then the statement can be executed a) UPDATE on R b) EXISTS on T c) SELECT on R d) UPDATE on R(a)