Which of the following, if true, most seriously weakens the argument? A. Although the percentage of flights that arrived on time dropped slightly overall, from 77 percent in 1998 to 76 percent in 1999, some United States airlines' 1999 on-time rate was actually better than their 1998 on-time rate. B. The number of passengers flying on United States airlines was significantly higher in 1999 than in 1998. C. Fewer bags per 1,000 passengers flying on United States airlines were lost or delayed in 1999 than in 1998. D. The appearance in 1999 of many new Internet sites that relay complaints directly to the Department of Transportation has made filing a complaint about airlines much easier for consumers than ever before. E. Although the number of consumer complaints increased for every major United States airline in 1999, for some airlines the extent of the increase was substantial, whereas for others it was extremely small.