Refer to the figure above, which shows a country's possible production possibility frontiers and indifference curves. If the country is producing at ________, then moving to ________ will cause utility to ________( )
选项：

A:point b; point c; remain unchanged
B:point c; point b; decrease
C:point a; point b; increase
D:point a; point c; remain unchanged
E:point c; point b; increase