The correct classifications are as follows:
- Mesopotamia and Greece are not both river valley civilizations; Mesopotamia is, but Greece is considered a classical civilization.
- Greece and Rome are indeed classical civilizations.
- West Africa and China: While China is considered a classical civilization, West Africa is typically associated with its own unique civilizations, like the Mali Empire, rather than being classified as a classical civilization.
- Egypt is considered a river valley civilization, while the Indus Valley civilization is also a river valley civilization. They are not classified as classical civilizations.
So, the statement "Greece and Rome are classical civilizations" is the only entirely accurate one among these options.