Final answer:
The Athenian Assembly operated as a lawmaking group with the authority to pass laws and reverse decisions, hence, the correct answer is D. all of the above.
Step-by-step explanation:
Regarding the assembly in the city-state of Athens, D. all of the above is true. The Athenian Assembly was indeed a vital part of Athenian democracy. It functioned as a lawmaking group, with the power to pass laws, including declaring war and approving treaties.
Moreover, it could reverse decisions, thus acting as a check on other parts of the government. This participation was limited to male citizens of Athens, who could be chosen by lot to sit in the Council. Positions of authority were, to various extents, determined by the wealth of the citizens.