According to the passage, one significant implication of the discovery that neutrinos have mass is that such a discovery would A. cast doubt on the solar origins of many of the neutrinos that reach Earth B. help to establish the validity of the standard particle-physics model C. indicate that most of the visible matter of the universe is composed of neutrinos D. entail that the total weight of all the visible matter in the universe is less than that of all the neutrinos in the universe E. mean that the speed with which neutrinos normally move can be slowed by certain types of matter