There is usually a large black market presence in which economy?
all modern economies use some combination of and
a. capitalism . . socialism
b. market forces . . capitalism
c. central planning . . government
d. market forces . . central planning

D. Market Forces and Central Planning

All modern economies use some combination of market forces and central planning.

Hope this helps! :)

john maynrd keynes developed new economic respose to the                           ( b. great depression if the 1930's)