Both conventional cars and hybrid cars with electric motor cause air pollution,but the latter one causes less air pollution as compared to the conventional cars.
The conventional cars use petrol and diesel as their fuel which after ignition produces more amount of pollutants. On the other hand most of the hybrid cars are gas electric hybrids. They use the same fuel just like conventional gas engine, but they produce less pollutants .It is so because we are using electric motors which moves at a very low speed .In this way the electric motor increases its fuel efficiency .The battery of the hybrid cars are charged by gasoline engines.
A hybrid car with electric motor does not require any solar panels for power.
Hence the correct option out of the four options given in the question will be ' b' i.e the cars with hybrid and electric motors cause less air pollution.