The average 40-year-old North American will have watched more than one million TV commercials in his or her lifetime. We may safely conclude, ttherefore, that the TV commercial has influenced North American habits of thought. The conclusion above follows logically if which one of the following is assumed? ['Anything people are exposed to in great quantity will influence their habits of thought.', 'It is impossible to avoid or ignore television commercials.', 'Some people find television commercials more interesting to watch than the programs themselves.', 'The habits of thought that people develop are largely determined by external influences.']