What would result from implementing higher average fuel-efficiency standards? 

A)  it would reduce energy waste 
B)  it would increase air pollution 
C)  it would increase emissions of heat-trapping carbon dioxide 
D)  it would cost jobs

By implementing higher average fuel-efficiency standards, it will reduce energy waste. This is because vehicles will be able to travel greater distances with the same amount of fuel, leading to a decrease in the amount of fuel consumed overall. This reduction in fuel consumption will result in lower greenhouse gas emissions, which will help to mitigate climate change. It is unlikely to increase air pollution, emissions of heat-trapping carbon dioxide, or cost jobs, as these negative outcomes are not a direct result of higher fuel efficiency standards.