A consumer magazine surveyed people who had sought a psychologist’s help with a personal problem. Of those responding who had received treatment for 6 months or less, 20 percent claimed that treatment “made things a lot better.” Of those responding who had received longer treatment, 36 percent claimed that treatment “made things a lot better.” Therefore, psychological treatment lasting more than 6 months is more effective than shorter-term treatment.
Which one of the following, if true, most seriously weakens the argument?
(A) Of the respondents who had received treatment for longer than 6 months, 10 percent said that treatment made things worse.
(B) Patients who had received treatment for longer than 6 months were more likely to respond to the survey than were those who had received treatment for a shorter time.
(C) Patients who feel they are doing well in treatment tend to remain in treatment, while those who are doing poorly tend to quit earlier.
(D) Patients who were dissatisfied with their treatment were more likely to feel a need to express their feelings about it and thus to return the survey.
(E) Many psychologists encourage their patients to receive treatment for longer than 6 months.
Source: LSAT