The most important difference between a republic and a democracy among the options provided is:
Republics, and not democracies, elect people to represent the citizens.
In a republic, elected representatives make decisions on behalf of the citizens, often within the framework of a constitution that protects certain individual rights. In a direct democracy, citizens vote directly on policies and laws. While the terms can overlap in modern usage, this distinction is fundamental in understanding the structure and function of governance in different systems.