(A) 4-5 times a year
(B) ** once a year
(C) during a crisis
(D) every month
EXPLANATIONS BELOW
Concept note-1: -The General Assembly meets annually in regular session, intensively from September to December, and resumes in January until all issues on the agenda are addressed – which often is just before the next session starts.
Concept note-2: -According to the Aristotelian Constitution of the Athenians (Ath. Pol. 43.4), the Assembly in Athens met four times every prytany. At each one of these meetings certain topics had to be discussed or voted on.
Concept note-3: -It originally met once every month, but later met three or four times per month. The agenda for the ekklesia was established by the Boule, the popular council. Votes were taken by a show of hands, counting of stones and voting using broken pottery.
Concept note-4: -In the Athens of the 5th and 4th centuries bc, the prytaneis, a committee of the Boule (council), summoned the Ecclesia both for regular meetings, held four times in each 10th of the year, and for special sessions.
Concept note-5: -The Pnyx was the official meeting place of the Athenian democratic assembly (ekklesia). In the earliest days of Athenian democracy (after the reforms of Kleisthenes in 508 B.C.), the ekklesia met in the Agora. Sometime in the early 5th century, the meeting place was moved to a hill south and west of the Acropolis.