Instrumental behavior can be reinforced in which two general ways?
a. positive reinforcement and negative reinforcement
b. reward and punishment
c. compulsion and reward
d. motivation and pain

The correct option is A.
Instrumental behavior refers to an action which is performed in order to achieve a goal. Instrumental behavior can be modified by the behaviors consequences.
Positive reinforcement occur when the instrumental behavior is rewarded.

The answer is (A) remain constant.

This is because today, the averae family size is 2 children per couple. The population will decline, but to a small extent.