which sentence is punctuated correctly?

a i added bread, milk, and sugar to the list of ingredients needed to make the recipe
b baking bread is one of my favorite things to do- on a weekend afternoon
c before you leave for the store... check to make sure your grocery list is complete
d because, we live at a high elevation, sometimes we have to adjust the cooking time for recipes

C Before you leave for the store, check to make sure your grocery list is complete.