Final answer:
The store is increasing task utility by helping customers carry groceries out to their cars, providing a service that adds value to the shopping experience.
Step-by-step explanation:
By offering to help customers carry their groceries out to their cars, the store Sara prefers to shop at is increasing task utility. Task utility involves making it easier for customers to use a product by providing additional services or conveniences. In this case, the grocery baggers add value to the shopping experience by assisting customers with a task they might find difficult or cumbersome.