Label the following as True, False, or Uncertain and explain your choice. (Uncertain means that it can be either true or false depending upon the circumstances).

a. The imposition of a tax on currently uncontrolled greenhouse gas emissions would represent a move toward efficiency.

b. Relying on a series of regional systems (like the EU ETS), rather a true global system, for controlling greenhouse gases increases the importance of the leakage problem.

c. The marginal external cost rule is designed to harmonize private and social incentives for global environmental problems.