What is the relationship between paragraphs 3 and 4 in the passage? A. Paragraph 3 explains why a need for leadership arose in early civilizations, and paragraph 4 describes how that leadership developed. B. Paragraph 3 suggests that agriculture was first practiced in Asia and Africa, and paragraph 4 discusses how it might have later spread to the rest of the world. C. Paragraph 3 describes several methods of early government, and paragraph 4 gives an extended example of one of them. D. Paragraph 3 discusses a cause of the spread of river valley agriculture in early civilizations, and paragraph 4 discusses an effect.