Complex sentence: When the "balance" is decided at the discretion of users, the access control is called Discretionary Access Control (DAC) that is more tolerant of actions that manage risk where MAC requires risk avoidance.
Split into simpler sentences: When the "balance" is decided at the discretion of users, the access control is called Discretionary Access Control (DAC). DAC is more tolerant of actions that manage risk where MAC requires risk avoidance.