GMAT Sentence Correction (SC) | Re: Despite the growing number of people who purchase plane

Its the game of IDIOM here.

Right IDIOM IS PREFER "X" TO "Y" not Prefer "X" compared to or compare with "Y". Can quickly eliminate C, D, E.

B/W A & B:

A) growing number of people who purchase plane ticketsonline, airline executives are convinced that, just as one-third of bank customers still prefer human tellers to automatic teller machines , many travelers will..

Strike of bold and underline portion and you will find sentence still makes sense.
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