Explain how ancient egypt was isolated from other cultures by natural borders?

Ancient Egypt was protected from other civilizations by these natural boundaries, but that does not mean they had no contact with other civilizations. Egyptians traded with several of their contemporaries, especially the Greeks. Nevertheless, their relative isolation allowed their culture to develop uniquely.
Egyptians benefited greatly from their geography. In addition to the protection afforded by the nearby mountains, seas and deserts, they were able to develop an agrarian culture thanks to the annual flooding of the Nile River. Each year, the river would swell and eventually overrun its banks, flooding vast areas of flat ground near the river. When the waters receded, the soil was fertile and full of moisture. The combination of the flood-enriched soil and nearly constant warmth and sunshine allowed the region to farm crops successfully.

Where are the following

Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.