Total points: $\frac{3}{25}$

Subway, a chain known for its fresh, made$-$to$-$order sandwiches, has launched the Green Goddess Tuna Melt in its U$.$S$.$ restaurants. The sandwich features flaked tuna blended with mayonnaise, topped with shredded mozzarella cheese, and toasted on nine$-$grain bread. It is then layered with fresh spinach, tomatoes, onions, and green goddess dressing. Subway is the first national quick$-$service restaurant chain to use Green Goddess dressing on a sandwich. Subway's offering of the Green Goddess Tuna Melt is an example of which of the following types of new products?

An improvement or a revision of an existing product

A repositioned product

A new$-$product line

An addition to an existing product line