400
Which heading best completes this partial outline?
I.
A. Natural boundaries of desert,mountains, and the sea
B. Yearly flooding to enrich farmlands
C. Old and Middle Kingdoms
D. Production of papyrus plant
A. Egypt-Gift of the Nile
B. Mesopotamia-Land Between the Rivers
C. China's Sorrow-Huang He River
D. Harappa-City on the Indus