题目选项分析

Countries that legalized the drug X twenty years ago, because a significant percentage of the population had been using X on a daily basis without any apparent harm to the community at large, reset the benchmark for what is appropriate and proper behavior among their citizens. Since X's legalization, there has been an increase in manic depression, suicide and certain kinds of cancer. In order for Andovia, a country that has not yet legalized X,to avoid the development of such undesirable tendencies and prevent the social problems stemming from broad usage of drug X, it should close its borders and not issue visas to any tourists from countries where drug X is legal.

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

【选项】Drug X is very easy to extract chemically from certain consumer products and is taken in droplet size doses that can easily be camouflaged as items such as hairspray or nail polish remover.