Over twenty years ago, in a landmark experiment in the psychology of choice, professor Sheena Iyengar set up a jam-tasting
booth at a grocery store. The number of jams available for tasting ______ some shoppers had twenty-four different options,
others only six. Interestingly, the shoppers with fewer jams to choose from purchased more jam.
varied:
varied,
varied, while
varied while
Choice A is the best answer. The convention being tested is the use of a colon within a sentence. In this choice, the colon is
used in a conventional way to introduce the following description of how the number of jams available varied. 
Choice B is incorrect because it creates a comma splice. A comma can’t be used in this way to join two main clauses (“the
number…varied” and “some…six”). Choice C is incorrect because it results in an illogical and confusing sentence. Using the
conjunction “while” to join the main clause (“the number…varied”) with the following clause’s description of the number of
jams available suggests that the variation in the number of jams is in contrast to some shoppers having twenty-four options.
Choice D is incorrect because it results in an illogical and confusing sentence. Using “while” in this way suggests that the
number of jams available varied during the time in which some shoppers had twenty-four options and others had six. The
sentence makes clear, however, that what follows “varied” is a description of the variation, not a separate, simultaneous
occurrence.