Final answer:
The correct answer is option C) Amphipolis.
Step-by-step explanation:
Around 465 BC, the Athenians founded a colony at Amphipolis, strategically located on the Strymon River. This was during a period when Athens was expanding its influence through the Mediterranean and Black Sea regions after the establishment of democracy.
The region provided valuable resources and a military advantage for controlling trade routes. Amphipolis became an important city in the Athenian empire during the classical period. The founding of this colony highlights Athens' growth from a city-state to a significant imperial power in ancient Greece.