Which of the following public policies is an example of a price ceiling?

In the above table, if the market is perfectly competitive and unregulated, at the equilibrium level of output, the marginal social benefit per unit is

A) zero. B) $20 per unit. C) $50 per unit. D) $70 per unit.

At a price of $5, consumers buy 200 units of good X. When the price falls to $4, quantity demanded increases to 250 units. We can conclude that over this range, demand is:

A) elastic. B) unit elastic. C) inelastic. D) perfectly inelastic.