How did the Neolithic Revolution and geographic features contribute to the rise of river valley civilizations in Mesopotamia, Egypt, India, and China?

In presidential elections if no candidate receives a majority of the election votes, a. the winner is decided by the house of representative’s. b. the current president remains in office for four more years. c. the winner is decided by the senate. d. a runoff election is held in december between the two candidates who received the most votes in the general election.