Independent variable is to dependent variable as _____ is to _____

If players can communicate or if iterated prisoner's dilemma games are used, then

players are (a) more likely to cooperate than in a prisoner's dilemma played just once (b) compete because of pure incentive considerations (PICs) (c) likely to suffer from competition burnout and quit the game (d) contribute to the tragedy of the commons

Which theory of pitch best accounts for the perception of sounds between 1,000 and 4,000 cycles per second?

a. place theory b. gate-control theory c. frequency theory d. opponent-process theory e. volley principle