Which ingredient is used to garnish the Key Lime Pie?

In the preparation of a Key Lime Pie, graham cracker crumbs are used as a key element in both the crust and as an occasional garnish. The crust is typically made by mixing crushed graham crackers with butter and sugar to create a crumbly base that holds the pie together. While it is more common for graham cracker crumbs to be associated with the pie's crust, they can also be sprinkled on top of the pie as a garnish, adding texture and reinforcing the flavor profile.

The other options do appear in desserts but are not traditional garnishes for Key Lime Pie. Chocolate shavings would introduce a flavor that competes with the tartness of lime, fresh fruit is not a typical garnish for this pie, and mint leaves, while they can complement lime in other contexts, are not typically used with Key Lime Pie. Thus, graham cracker crumbs stand out as the most appropriate choice, both for their historical use and flavor harmony.