Final answer:
The type of rack used to store extra sub rolls for use that day is called a speed rack. Speed racks are metal storage racks with multiple shelves that are designed for commercial kitchens or restaurants.
Step-by-step explanation:
The type of rack used to store extra sub rolls for use that day is called a speed rack. A speed rack is a metal storage rack with multiple shelves that is designed to hold and organize food items, including sub rolls, in a commercial kitchen or restaurant.
Speed racks are typically made of durable materials like stainless steel and have open wire shelves to allow for airflow and easy cleaning. They often have wheels for mobility and can be easily moved around the kitchen as needed.
By using a speed rack, restaurants can efficiently store and access their sub rolls, ensuring they are fresh and ready to be used throughout the day.