Final answer:
The Athenians refused to grant the Melians their request to remain neutral, believing that their own power and self-interest justified their actions.
Step-by-step explanation:
The Athenians sternly replied that they would not grant the Melians their request to remain neutral. The Athenians argued that it was in their best interest to conquer the Melians and bring them under their control. They believed that the strong should rule over the weak, and that their own power and self-interest justified their actions.