Reserved powers are given to whom?

Which statement best explains why article iii of the constitution gives congress the ability to create lower courts inferior to the supreme court "from time to time”? a.the framers of the constitution believed that as the country grew, more courts would be needed to meet its needs. b.the framers of the constitution believed that as courts made unpopular decisions, they would need to be replaced. c.the framers of the constitution wanted to ensure that congress always had more power than the courts. d.the framers of the constitution wanted to ensure that new courts were always being created so new judges could be appointed.