About 3,500 years ago, the city of now called santorini, was destroyed by a volcanic eruption.

Akrotiri
The city was an important center in the ancient civilization of Minoa. The bronze age settlement was in present day Santorini, also known as Thera,itself a volcanic island. Historians believe that the ancient Minoan civilization which preceded classical Greece, and the city of Akrotiri was destroyed by volcanic eruption.

The answer is option a. boundary line drawn by pope alexander iv in 1493.