Under the Emissions Trading Scheme, If Lots of Firms Introduce

Under the emissions trading scheme, if lots of firms introduce emissions curbing technologies, the demand for permits:

A) might decrease and the firms' costs fall, while industry will expand, but the emissions will stay under the allowed cap.
B) might increase and their price fall increasing the costs to firms.
C) might decrease and their price rise leading to reduced output by the industry.
D) might increase and their price rise, resulting in lower costs to the firms and increased output by the industry.