Which executive officer is not elected by voters?

The State Revenue Commissioner is the correct answer because this position is appointed rather than elected. In Georgia, the State Revenue Commissioner is appointed by the governor, reflecting the state's design to allow the executive branch to fill certain positions with individuals who can carry out the administrative functions effectively without direct electoral pressure.

In contrast, positions such as the Commissioner of Labor, the Secretary of State, and the Commissioner of Agriculture are all offices that are filled through statewide elections, allowing citizens to directly participate in choosing their leaders for these roles. This distinction highlights the varying methods of selection for executive officers within the state's governance framework and emphasizes the importance of understanding the roles and methods of appointment or election for various government positions.