Because it was long thought that few people would watch lengthy televised political messages, most televised political advertisements, like commercial advertisements, took the form of short messages. Last year, however, one candidate produced a half-hour-long advertisement. During the half hour the advertisement was aired, a substantial portion of the viewing public tuned into the advertisement. Clearly, then, many more people are interested in watching lengthy televised political messages than was previously thought.Which of the following is an assumption on which the argument depends?
【选项】Most of the viewers who tuned in to the candidate's half-hour-long advertisement last year did not change channels after the first few minutes.