______ is the official minimum rate at which the central bank of a country is prepared to rediscount approved bills held by banks.

Bank rate is the rate at which the central bank (RBI in India) rediscounts first-class bills like commercial bills and government securities held by commercial banks. It is the official minimum rate for such rediscounting operations. CRR is the cash reserve ratio, SLR is statutory liquidity ratio, and repo rate is the rate at which banks borrow from RBI overnight - none of these refer to rediscounting of approved bills.