Final answer:
Ancient Greek democracy, particularly in Athens, operated as a direct democracy where citizens could vote on laws directly, differing from the current American representative democracy where citizens elect officials to decide on laws. The key difference lies in the direct input on laws which was prevalent in ancient Greece but not in the modern United States.
Step-by-step explanation:
When we compare and contrast we look for similarities and differences between two subjects. One way democracy in Ancient Greece was different than our current American democracy is in the execution of democracy itself, particularly the use of a direct democracy vs. a representative democracy. In ancient Athens, a system known as direct democracy was in place, where citizens had the ability to vote directly on laws and important policies. This is notably different from the United States' representative democracy, where citizens elect officials to make decisions on their behalf.
In ancient Greece, specifically within the city-state of Athens, not everyone was eligible to vote. Estimates suggest that approximately 15% of the population had the right to do so. Moreover, those who could vote participated in a direct manner by attending the Assembly to both debate and vote on all proposed legislation, which contrasts the modern process in which Americans vote for representatives who decide on laws in the nation's legislatures.
Therefore, the correct answer is A. The ability of citizens to have direct input on the creation of new laws. This reflects the key difference that Ancient Greek citizens were directly involved in the law-making process, unlike in the United States today where the general public influences legislation indirectly through elected representatives.