Last year Comfort Airlines had twice as many delayed flights as the year before, but the number of complaints from passengers about delayed flights went up three times. It is unlikely that this disproportionate increase in complaints was rooted in an increase in overall dissatisfaction with the service Comfort Airlines provides, since the airline made a special effort to improve other aspects of its service last year. Which of the following, if true, most helps to explain the disproportionate increase in customer complaints? ['The average length of a flight delay was greater last year than it was the year before.', 'Some of the improvements that Comfort Airlines made in its service were required by new government regulations.', 'The average number of passengers per flight was no higher last year than the year before.', 'Comfort Airlines had more flights last year than the year before.']