Which early greek city-state controlled access to the hellespont (dardanelles strait) ?

The correct answer is Troy

Troy was very strong and famous in the Hellenic times and was the center piece of the Iliad and even the Odyssey is related to it because Odysseus is coming home from fighting in Troy. Nowadays, it is located in the territory of Turkey in the region of Asia Minor. They controlled both the strait and the seas because of their power.