Which statements about the delian league are true?

choose all answers that are correct.

a.
the league failed to protect greece from the persians, and the city-states were conquered.

b.
the purpose of the league was to keep sparta from gaining too much power.

c.
when some city-states tried to withdraw, athens used force to keep them under control.

d.
sparta never joined the league and resented athens’s power and treatment of allies.