A mоther brings her 16-mоnth-оld son in for аn evаluаtion. She is afraid he is not meeting his developmental milestones and wants to know if he should be sent to therapy. He was the product of an uneventful pregnancy and a spontaneous vaginal delivery. His Apgar scores were 7 and 9. Until reaching a year old the mother believes he was hitting his milestones appropriately. You decide to administer the Denver Developmental Screening Test. You find that he is using a spoon to eat with and can take off his own shoes and shirt. He can build a tower of two cubes and dump raisins. His vocabulary consists of at least 10 words. He can stand alone and stoop and recover, but he is unable to walk without holding onto someone's hand.What type of developmental delay does he have?