How does the u s constitution republic compare to authoritarian forms of government?

In a constitutional republic like the US, the head of state and other representatives are chosen by the population. There is also a constitution, which limits the power of the members of the government, and guarantees separation of powers - Legislative (the making of the laws), Executive (the realization of these laws), and Judicial Branch (which decides if these laws have been broken).

On the other hand, authoritarian forms of government are:

what are the choises i cant answer without choises