Final answer:
The nurse should suggest to the mother to shorten the duration of story sessions and gradually increase as attention improves.
Step-by-step explanation:
The nurse should suggest option a. Shorten the duration of story sessions and gradually increase as attention improves to the mother. Children with attention deficit-hyperactivity disorder (ADHD) often have difficulty maintaining focus for extended periods of time. By shortening the duration of story sessions and gradually increasing them as the child's attention improves, it allows the child to practice focusing without becoming overwhelmed or distracted.