Which statement best describes the impact of medical advances on global standards of living?

A. Medical advances generally improved standards of living for people in developed and developing nations.
B. Medical advances improved the standard of living for most people in developed nations, but only for few people in developing nations.
C. Medical advances improved the standard of living for most people in developing nations, but only few people in developed nations.
D. Medical advances has limited impact on a majority of people in developed or developing nations.