Which of the following is a good example of behavior modification for changing snacking behavior?
 a. When I want a snack I'll take a 20 minute walk and reevaluate whether or not I still want it.
 b. When I want a snack I'll take only half of what I really wanted.
 c. I won't purchase any extra food.
 d. I won't eat dessert so I can have snacks throughout the day.