According to paragraph 1, which of the following is true of early food production by the end of the Pleistocene?

• In certain areas of western and central Africa, some people were already growing root plants such as yams.
• The cultivation of cereal crops had already been used effectively and widely by people living on the fringes of ram forests.
• Sophisticated forms of "vegeculture" were introduced for the first time in central and western Africa by people from the Sahara's southern borders.
• The cultivation of root and tree crops replaced the cultivation of cereal crops because of decreasing summer rainfall in grassland areas.

This is a multiple choice.