Now suppose competition among several market makers forces the spread down to $4 . How many goods are traded?

At a competitive equilibrium, if there are no taxes, subsidies, price regulations, quantity regulations, or externalities,

A) the marginal benefit is greater than the marginal cost. B) resource use is efficient. C) the marginal benefit is less than the marginal cost. D) both the marginal benefit and the marginal cost of the last unit produced equal zero. E) the marginal benefit is greater than the marginal cost by as much as possible.

With the real wage on the vertical axis and employment (N) on the horizontal axis, we know that

A) the WS curve is upward sloping. B) the WS curve is downward sloping. C) the PS curve is upward sloping. D) the PS curve is downward sloping.