Becky's mother is a school teacher and her father is a manager of a large department store. Becky left home at age 16 to live with her bf and when their relationship broke up, Becky no longer communicated with her parents and did not return to high school. After working briefly at a fast-food restaurant, Becky started panhandling (asking for money from passers by) at a shopping area located adjacent to a large university. Becky's brother, Bill, on the other hand, became a practicing brain surgeon who also teaches at a major medical school. Becky's situation is an example of _______ mobility. Bill is experiencing ______ mobility. Select the best suitable words from the following ;
(a) Vertical , horizontal
(b) Vertical, Vertical
(c) Horizontal, Vertical
(d) Horizontal, Horizontal