Final answer:
Over-mixing pie dough usually leads to a tough and chewy crust due to excessive gluten development, which inhibits the creation of a flaky and tender crust.
Step-by-step explanation:
The result of over-mixing pie dough is typically c) Tough and chewy crust. When pie dough is mixed too much, the gluten in the flour begins to develop excessively, creating a stronger, more elastic dough. This heightened gluten development results in a crust that lacks the desirable flaky and tender texture that is characteristic of a good pie. Ideally, pie dough should be mixed just enough to incorporate the ingredients, but not so much that the dough becomes tough.