The statement that best explains the differences between the democracy of the Athenian polis and the structure of the Roman Republic is:
The senate of the Roman Republic was composed of wealthy patrician magistrates whereas the Athenian ecclesia and Council of 500 were made up of various citizens drawn by lot from different territories within Athens.
This response highlights the contrasting social structures and political representation in the two systems, with the Roman Senate being exclusive to the wealthy elite and the Athenian system allowing broader citizen participation.