Methods to Prevent Pollution from Motor Vehicle Emissions Include All

Methods to prevent pollution from motor vehicle emissions include all of the following except

A) improving fuel efficiency and modifying the internal combustion engine to reduce emissions.
B) raising annual registration fees on older, more polluting cars.
C) increase the legal driving age.
D) giving subsidies to car makers for each low-polluting, energy-efficient car they sell.
E) restricting driving in polluted areas.