1.3 Which of the following is an assumption under which the production possibilities frontier is drawn?
a) Total unemployment is zero.
b) The supply of resources is fixed.
c) The price level is changing.
d) Technology is changing.

answer; researchers typically cannot control people's sexual behaviors as would be necessary in an experiment;

answer; i believe the correct answer is (4) flip a coin as each participant arrives,heads indicates assignment to the first group: tails indicates assignment to the second group;