D all of the above. The marginal value of a good A is measured by what would be forsaken for another increment of the particular good. B is the same as the total value of the good. C is only slightly less than the total value of the good. D is what an individual would be willing to pay the marginal firm for the good.
Consumer surplus is A the gains from exchange.
B the difference between total expenditure and total value. C the difference between what one would pay and what one does pay. D all of the above. The Law of Demand is derived from A the property of increasing total values. B thin air.