Well, Velocity is the speed of something in a given direction, and speed is the rate at which someone or something is able to more or operate. They both invlove speed, so this is a hard one, but I wold say either B or D
the person on the boat is moving 15mph on the boat and throws the ball 10mph. you add that together its 25mph. the other person is standing on land so their is no extra speed.
Ohms law states that current is directly proportional to the potential difference across the ends of a conductor provided that temperature and other factors kept constant
