The Diagram Below Shows a Market for Tradable Pollution Permits

The diagram below shows a market for tradable pollution permits.
Figure 17- 7
-Refer to Figure 17- 7,which depicts a market for tradable pollution permits.Improvements in firms' abatement technology will be expected to

A) not have any impact on the equilibrium.
B) shift the supply curve to the left.
C) shift the demand curve to the right.
D) shift the demand curve to the left.
E) shift the supply curve to the right.