Answer: A. Scheme
Explanation: Jean Piaget was a Swiss psychologist known for his work on child development and he's known to have placed a great importance on the education of children. Piaget believed that the basic building blocks of the way children understand the world are mental structures called schemes.
A scheme can therefore be defined as a set of linked mental representations of the world which is used to understand as well as respond to situations. The actions of the 4month old baby is the baby's way of trying to understand what the toys mean and represent in relation to his world, according to Piaget's theory.
