A single price monopoly that faces the demand curve P = 10 - Q and profit maximizes by reducing price from $6 to $5 must have a marginal cost of  

Assumptions are necessary to

A) make economics a social science. B) define a set of circumstances where a model is most likely to apply. C) define the relationship between wants and resources under all circumstances. D) define the specific cause and effect relationship that is being explained by social sciences.

Buck carefully plans out an early morning exercise routine to lose weight and get fit. When it's time to work out, however, Buck just "doesn't feel up to it" and decides to sleep in. Behavioral economics would say that Buck:

A. weighed the costs and benefits and made a rational economic decision to sleep in. B. used System 1 of his brain to formulate his workout plan, but then gave in to System 2 when he chose to sleep in. C. used System 2 of his brain to formulate his workout plan, but then gave in to System 1 when he chose to sleep in. D. is fundamentally lazy and incapable of sticking to a workout plan.