Editorial: The gates at most railroad crossings, while they give clear warning of oncoming trains, are not large enough to prevent automobile drivers from going around them onto the tracks. Some people claim that the ensuing accidents are partly the fault of the railroad company, but this is a mistake. Granted, if one has a small child in the house, then one ought to block access to stairs completely; but a licensed driver is a capable adult who should know better. The editorial's conclusion follows logically if which one of the following is assumed? ['Small children are not involved in accidents resulting from drivers going around the gates.', 'Capable adults have a responsibility to take some measures to ensure their own safety.', 'The gates could be made larger, yet irresponsible drivers might still be able to go around them onto the tracks.', 'When the warnings of companies are disregarded by capable adults, the adults are fully responsible for any resulting accidents.']