Which of the following is not a lunch item?

The Breakfast Jack is indeed a breakfast item and is typically not considered a lunch offering at Jack in the Box. It features a more traditional breakfast combination of eggs, a slice of cheese, and a protein like ham or bacon all served on a bun. This focus on breakfast elements sets it apart from the other options listed.

In contrast, the Bacon Nacho Tacos, Club Salad, and Grilled Chicken Salad are items that fit well within the lunch menu. These options include ingredients that are commonly associated with lunch dining, such as meats, vegetables, and more substantial combinations. Hence, identifying the Breakfast Jack as the sole breakfast item helps clarify its distinction from lunch offerings.