The correct answer is D) the concept of citizenship.
The legacy of the ancient Greeks that is important to all modern democracies is the concept of citizenship.
It was Solon, the great Greek leader, who set the foundation of democracy in ancient Athens. Years later, Athenian leader Cleisthenes contributed to the spread of democratic ideas in the 6th century BC. Democracy created concepts such as citizenship and the right of people to elect their rulers.
