What term describes the practice of adding new product items into an existing product line to fill gaps or extend market reach?

Explanation

* Product Line Filling adds more items within the present range of the line (e.g., adding intermediate size choices).
* Product Line Stretching occurs when a firm lengthens its line beyond its current range (downward, upward, or both ways).
* Line filling must create distinct items to avoid internal product cannibalization.