A new medication for migraine seems effective, but there is concern that the medication might exacerbate heart disease. If patients with heart disease take the medication under careful medical supervision, however, harmful side effects can definitely be averted. The concern about those side effects is thus unfounded. The argument depends on which one of the following assumptions? ['The new medication has various other side effects, but none as serious as that of exacerbating heart disease.', 'No migraine sufferers with heart disease will take the new medication except under careful medical supervision.', 'The new medication actually is effective when taken by patients with heart disease.', 'The new medication will displace all migraine medications currently being used.']