Polls have shown that a higher percentage of graduating university students are against proposals to reduce government social services than are students entering their first year at a university. These polls lead us to the conclusion that people with a university education are more likely to favor retaining or increasing the present level of government social services than are members of the overall population. Which one of the following, if true, most seriously weakens the argument? ['Polls of retired persons who have not graduated from a university show a higher percentage of persons in favor of reducing government social services than do polls of retired persons who have graduated from a university.', 'Polls of those who graduated from a university more than five years before being polled show a higher percentage of people in favor of reducing government social services than do polls of the overall population.', 'In the polls cited, graduating university students were more likely to express strong opinions about the question of reducing government social services than were students entering a university.', 'The polls of graduating university students were designed to avoid overrepresenting any single academic discipline.']