Final answer:
In category management, defining and segmenting the category is part of the category plan development.
Step-by-step explanation:
True. Defining and segmenting the category is indeed part of the category plan development in the category management model. In category management, businesses analyze their product categories and segment them into groups based on specific criteria such as customer demographics, needs, and purchasing behavior. This segmentation helps businesses better understand their target customers and develop strategies to meet their specific needs.