which sentence is punctuated correctly?

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

c. I added bread, milk, and sugar to the list of ingredients needed to make the recipe.