Industrial accidents are more common when some of the people in safety-sensitive jobs have drinking problems than when none do. Since, even after treatment, people who have had drinking problems are somewhat more likely than other people to have drinking problems in the future, any employer trying to reduce the risk of accidents should bar anyone who has ever been treated for a drinking problem from holding a safety-sensitive job.

Which of the following, if true, most seriously undermines the argument above?

【选项】People who hold safety-sensitive jobs are subject to stresses that can exacerbate any personal problems they may have, including drinking problems.