Generic drugs contain exactly the same active ingredients as their brand-name counterparts, but usually cost much less to develop, produce, and market. So, generic drugs are just as effective as their brand-name counterparts, but cost considerably less. Which one of the following, if true, most strengthens the argument? ['Generic drugs are no more likely than brand name drugs to suffer from defects in composition.', 'Generic drugs are just as likely as brand-name drugs to be readily available in pharmacies.', "The higher costs of brand-name drugs underwrite drug companies' heavy investment in research.", 'Because of advertising, doctors frequently prescribe brand-name drugs by their brand name, rather than by their chemical name.']