In an effort to increase revenues, Sky Air recently

In an effort to increase revenues, Sky Air recently partnered with several airlines to create a joint frequent-flier program. In the new program, miles
earned on all partner airlines can be combined for reward tickets valid on any airline in the partnership. Sky Air’s CEO cites a recent increase in the number of passengers on all the partner airlines as evidence that the new frequent-flier program is having the desired effect. Industry analysts doubt the CEO’s claim.

Which of the following, if true, best supports the analysts’ position?

a) Air travel tends to be seasonal, with more passengers traveling during warmer months and holiday periods.
b) The recent increase in passenger rates for all the partner airlines was preceded by the lowest rates of air travel in the last decade.
c) Many travelers achieved reward tickets more quickly under the new frequent-flier program and redeemed them recently for free travel.
d) Travelers redeemed frequent-flier rewards on Sky Air’s partners more frequently than on Sky Air.
e) A study of frequent-flier programs showed that they generally result in increased long-term airline revenues.