What can be substituted with the lunch pizza for an additional cost?

The correct answer is the Small Caesar Salad, which can be substituted for the lunch pizza for an additional cost. This substitution is often popular because the Caesar salad complements the pizza format while still providing a different flavor profile and textural experience. The Caesar salad typically includes crunchy romaine, creamy dressing, and cheese, which enhances the overall lunchtime offering.

In contrast, the other salad options, while they may be delicious, may not specifically be on the substitution list provided by Cheesecake Factory for this particular menu item. Therefore, while they can be enjoyed separately, they may not adhere to the specified substitution policy for the lunch pizza.