Which sentence is punctuated correctly?

Question

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

Answer 1

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