The correct answer is “B,” as reported in “Successful Direct Marketing Methods” by Bob Stone, Sixth Edition, NTC Business Books, 1997, page 203.
“Buy one, get one free” outpulled the other offers by 40%.
There are two lessons contained in this test result.
FIRST, you can never say with absolute certainty what is going to work in direct marketing. The only way to determine the winner is through a test.
SECOND, you can ignore those who tell you “free” is overused, hokey, downscale, or whatever.
Smart marketers continue to use “free” because it WORKS — and for no other reason.