Proponents of the electric car maintain that when the technical problems associated with its battery design are solved, such cars will be widely used and, because they are emission-free, will result in an abatement of the environmental degradation caused by auto emissions. But unless we dam more rivers, the electricity to charge these batteries will come from nuclear or coal-fired power plants. Each of these three power sources produces considerable environmental damage. Thus, the electric car __. Which one of the following most logically completes the argument? ['will have worse environmental consequences than its proponents may believe', 'will probably remain less popular than other types of cars', 'will not produce a net reduction in environmental degradation', 'requires that purely technical problems be solved before it can succeed']