Which system has the President serving as both head of state and head of government?

In a presidential system, the President serves as both the head of state and the head of government, consolidating both ceremonial and executive powers in one office. This means that the President represents the nation at official functions and also has significant authority to govern, implement policies, and lead the executive branch. This dual role is a hallmark of presidential systems, allowing for a clear separation of powers between the executive, legislative, and judicial branches.

In contrast, in parliamentary systems, the head of state (often a monarch or ceremonial president) is distinct from the head of government (the prime minister), leading to a division of roles. Confederations typically involve a union of sovereign states that delegate limited powers to a central authority, lacking an executive leader like a president in charge of both roles. An oligarchy features control by a small group of individuals, without a formalized structure like that of a presidential system or separate heads of state and government. Therefore, the correct answer reflects the unique consolidation of powers within a presidential system.