Final answer:
The strongest evidence for hydrogen-fueled cars is that hydrogen fuel cells only produce water as a by-product, offering a clean energy source for vehicles without harmful emissions.
Step-by-step explanation:
The strongest evidence for the argument that we need hydrogen-fueled cars can be found by considering the advantages of hydrogen as a clean energy source. The statement that provides the strongest support is that hydrogen-based fuel cells only produce water as a by-product, found in excerpts discussing how fuel cells have been used in manned space vehicles and are now being reconsidered for use in electric cars due to their potential as cleaner energy sources. This is because, not only does hydrogen combustion not produce harmful emissions, the technology to generate electricity from fuel cells is already in place, and if this energy can be harnessed for automobiles, it could lead to a significant reduction in environmental pollution.