Which feature is the primary mechanism for maintaining the separation of powers in a presidential system?

💡 Explanation:

A presidential system is characterized by a strict separation of the executive and legislative branches (Separation of Powers). The 'system of checks and balances' is the primary mechanism designed to prevent any one branch from acquiring excessive power by allowing each branch to limit or scrutinize the others' actions, thereby maintaining the functional separation. Options A and D are characteristics typically found in a Parliamentary System, where there is a fusion of the executive and legislative branches. Option B is also a feature of some Parliamentary or Semi-Presidential systems, not a Presidential one.