The most prestigious attorneys in law firm X are the ones who have shown the greatest ability to win cases. However, every year for the past five years, the average number of cases won by the most prestigious attorneys in law firm X has not been greater than the average cases won by the lower ranking attorneys. Which one of the following, if true, most helps to resolve the apparent discrepancy? ["None of the lower-ranking attorneys work on their cases with law firm X's prestigious attorneys.", 'Law firm X has a policy of giving the cases that will be most difficult to win to the prestigious attorneys.', 'All of the cases taken by law firm X deal with patent infringement or intellectual property.', 'Normally, it takes at least seven years for a new attorney at law firm X to be considered a prestigious attorney.']