Direct democracy is most commonly found in
large groups of people
large groups of states
small groups of people
small groups of states

Direct democracy is most commonly found in small groups of people. Why? Because small groups of people can more easily arrange between themselves how they should vote and it's much easier to count each vote which each person has to contribute towards.

When you have a large group of people or states, this gets much more complicated because you need representatives that all the different people vote for and who then represent the votes of their representatives.