diverse
When you are presented with questions such as this, the first thing that you need to do is to determine the relationship between the first two words. Thus, because “vaunt” and “flaunt” basically mean the same thing (they are synonyms), to correctly complete this sentence, you’ll need a synonym of “disparate.” One possible synonym is “diverse.” As such, one possible way of completing this sentence is as follows: Vaunt is to flaunt as disparate is to diverse.