Randy works for a vending machine company. One morning, he fills up a vending machine that is on the third floor of an office building. Later that day, Mark buys a can of Pepsi from that machine. He takes the full can to a nearby balcony and drops it three floors onto Carl, a coworker who recently started dating Mark's ex-girlfriend. Carl falls unconscious. Is Randy a cause in fact of Carl's injury? Is he a proximate cause? What about Mark?