Research by developmental psychologist Angeline Lillard (2008; Lillard & Else-Quest, 2006) found that children who attended ___ preschools were more advanced in both cognitive and social development than those attending other preschools. Waldorf Montessori Reggio Emilia the most academically strict

Answer: Montessori

Explanation:

Montessori preschool, as per research of Lillard and Else-Quest is the preschool in which children tend to freely indulge in activities that they can pursue as per age. They can learn individually in such school for cognitive development as well as social development with peers.

Other options are incorrect because Reggie, Emilia and most academically strict are not the preschools that made a child more advanced in social development and cognitive development. Thus, the correct option is Montessori.