The map shows the natural resources of Egypt.

A map titled Natural Resources of Egypt. A key shows Farmland in green and icons for Sandstone, Limestone, Fish, Gold, Papyrus, and Salt. A label for First Cataract is at the south end of the Nile River. Sandstone, Limestone, Papyrus, and Salt are located at the north end of the Nile River near the Mediterranean Sea. Fish are located in the Mediterranean Sea, Red Sea, and Arabian Sea. Papyrus is found along the full length of the Nile River on the western side. Salt is found along the northern half of the Nile River. Gold is found along the bottom half of the Nile River.

Which natural resource was most abundant in ancient Egypt?

salt
papyrus
limestone
sandstone