Food is shipped thousands of miles throughout our country using various types of transportation such as trucks, planes, and boats. food availability would be most affected by a shortage in which of the following energy sources?
coal
natural gas
petroleum
water power

Suppose you and your friend live on the same street d miles away from each other. between your house and your friend’s house there are n motorized scooters positioned at distances x1, x2, . . , xn miles from your house towards your friend’s house. each scooter has a battery that may or may not be fully charged. let’s say that the scooters can take you distances d1, d2, . . , dn miles down the road. each scooter also has a price p1, p2, . . , pn that it takes to activate. any time you encounter another scooter, you may take the new scooter and leave your old scooter behind. there is an additional scooter at your house that you start with and it can go distance d0 miles and it is free to activate: p0 = 0. you wish to go to your friend’s house minimizing the total amount of money spent activating the scooters. design a dynamic programming algorithm that returns the minimum cost to get to your friend’s house using scooters x0, . . , xn.