Ans. is 'a' i.e., Attention deficit hyperactive disorder * This child has: (i) Restlessness, (ii) Interrupting others (the class is unable to concentrate), (iii) Difficulty in playing quietly, (iv) Often leaves seat and roams around.* All are features of ADHD.Attention-deficit hyperactivity disorder* ADHD is one of the most common psychiatric problem in school age population. It usually arises in the first 5 years of life and is three times more common in boys than in girls.* ADHD is characterized by an age inappropriate hyperactivity, impulsiveness and inattention. Hyperactivity is usually the first symptom noticed.Diagnostic criteria of ADHD1) Six (or more) of the following symptoms of inattention have persisted for at least 6 months to a degree that is maladaptive and inconsistent with development level.2) Six (or more) of the following symptoms of hyperactivity impulsivity have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental leveli) Often make careless mistakesii) Often has difficulty sustaining attentioniii) Often does not listeniv) Often fails to follow through on instruction or of finish tasksv) Often has difficulty organizing tasks and activitiesvi) Often avoids tasks requiring sustained attentionvii) Often looses thingsviii) Often is easily distracted by external stimuliix) Often is forgetful in daily activitiesHyper activityi) Often fidgets or squirmsii) Often leaves seatiii) Often moves excessively (may feel restless)iv) Often has difficulty playing or engaging in leisure activities quietlyv) Is often "on the go"vi) Often talks excessivelyImpulsivityvii) Often blurts out answersviii) Often has difficulty awaiting turnix) Often inerrupts or intrudes on others