Task: Question Answering
Input (English): Background Paragraph: In a bakery, angel food cakes could be baked in a rack oven, revolving oven, convention oven, or small deck oven. A commercial bakery may use a tunnel or traveling oven.[7] When the cake has finished baking, it should have a golden brown color on the exposed area.[5] The final volume will generally be two to three times larger than the batter volume.[6]. 
Story: Two bakeries were famous in town for their angel food cakes. Tom's was a small bakery with various small ovens, took small orders and did some catering. Bill's bakery was large and produced angel food cake commercially, in vast quantities. 
Question: Which bakery used a tunnel oven to bake angel food cakes?
Output (English): Bill's.