Which of the following is a common garnish for a gin and tonic?

A lime wedge is a common garnish for a gin and tonic because it complements the botanicals in the gin and adds a burst of acidity that balances the drink's flavors. The citrusy notes of the lime enhance the overall tasting experience, making it refreshing and bright. This particular garnish not only adds visual appeal but also encourages the drinker to squeeze the lime into the gin and tonic, enriching the flavor profile further.

The other options do not serve the same purpose or complement the flavor of gin and tonic in the same way. An olive is typically associated with martinis rather than highball drinks. A mint sprig might work well with other cocktails but can overpower the delicate botanicals of gin. A cherry is often used in sweeter cocktails and doesn’t pair well with the crisp and refreshing notes of a gin and tonic.