Answer: The detail that supports the central idea is A. "Ancient Greek art and literature are still studied and enjoyed today".
Explanation: The sentence "Ancient Greek art and literature are still studied and enjoyed today" is directly linked to the central idea provided, which also makes reference to Ancient Greece ("on a sunny peninsula in southern Europe, surrounded by the clear blue waters of the Mediterranean Sea"). Moreover, the central idea refers to the ideas forged by the Greek and sentence A. alludes to Greek art and literature, which can be described as "ideas". Therefore, sentence A. is related to the central idea and supports it.