单项选择题(2) should choose ()
A. It not only made settlements possible and ultimately the building of cities but it also made available a reliable food supply.
B. Later came measures of value as commodity and money exchange became common.
C. In this area people settled along the riverbanks and practiced field agriculture.
D. After farming was developed in the Middle East in about 6500 BC, people living in tribes or family units did not have to be on the move continually searching for food or herding their animals.
E. As villages grew, the accumulation of more numerous and substantial goods became possible.
F. With a food surplus, a community could support a variety of workers who were not farmers.
G. The first great civilizations grow up along rivers.
H. In doing so they created the first calendars.