Final answer:
School refusal is most closely associated with Separation anxiety disorder, where a child experiences extreme distress at the prospect of being away from home or caregivers, making it a primary reason for avoiding school.
Step-by-step explanation:
School refusal is most likely in the condition of Separation anxiety disorder. This disorder is characterized by a child's excessive fear and anxiety about being away from home or loved ones to the point where it interferes significantly with daily activities, including attending school. Children with Separation anxiety disorder often find it extremely distressing to separate from their primary caregivers and may exhibit significant distress at the prospect of going to school or being apart from their parents or caregivers.
In contrast, while conditions such as Oppositional Defiant Disorder (ODD), Anorexia Nervosa, Obsessive Compulsive Disorder (OCD), and Autistic disorder can all potentially impact school attendance in different ways, Separation anxiety disorder is directly associated with a child's refusal to go to school due to the separation aspect.
Therefore, among the options provided, 3) Separation anxiety disorder is the condition most associated with school refusal.