FilmPro sells millions of videocassettes directly to consumers at $25 apiece for a $10 profit on each. However, FilmPro is losing money because people are buying illegally copied versions of its $25 videocassettes at far cheaper prices. So far, one million illegally copied cassettes have been sold for $5 each. Illegal copying, ttherefore, has cost the company at least $10 million in potential profits. Which of the following is an assumption that, if true, would allow the conclusion above to be properly drawn? ['The illegally copied tapes are of such high quality that it is virtually impossible to differentiate between them and the originals.', 'FilmPro never sells discontinued videocassettes at less than $25 apiece.', 'At least one million more cassettes would have been purchased from FilmPro for $25 apiece if the illegally copied cassettes had not been available.', 'The price of the illegally copied videocassettes never goes below $5 apiece.']