Final answer:
Behavior modification focuses on the observable and measurable aspects of behavioral change. This allows for the practical setting and assessment of SMART goals, where 'M' stands for Measurable, emphasizing the measurability of progress.
Step-by-step explanation:
The focus of behavior modification advocates can be encapsulated in the concept that behavior must be observable and measurable. When looking at behavior modification, the primary concern is whether changes in behavior can be directly seen and quantified. Hence, the correct answer to the student's question is "Observable and measurable behavior is the focus of behavior modification advocates." This emphasis on observable outcomes is essential not only for measuring the current state but also for assessing the progress of the intervention over time. This practical approach enables the setting of SMART goals, where "M" stands for Measurable, indicating the importance of being able to measure progress toward the achievement of a goal.