Correct Response: A. A motorcycle helmet contains energy-absorbing rigid foam beneath the outer plastic shell. After a helmet has sustained an impact during an accident, this foam is likely to have been compressed, and hence it will have lost some of its protective capability. Since the compression would occur between the foam and the outer shell, there is no way to detect it without disassembling the helmet. Therefore the helmet should be replaced. The absence of visible damage (B) does not ensure that the helmet is still effective. A high-quality, well-maintained helmet made with modern materials, and that has never been in an accident, should still be replaced every five years (C). The materials degrade with time and lose their energy-absorbing qualities. If the visor becomes scratched (D) and reduces visibility, it should be replaced. However, that is not a reason to replace the entire helmet.
