Richard Is a 5-Month-Old Baby

Richard is a 5-month-old baby.His parents frequently sit by his side to cuddle him or to speak to him in loud and affectionate tones.Richard seems to enjoy this attention very much and makes cooing sounds to encourage his parents' warm interactions with him.Richard's act of cooing to obtain parental attention is a function of the ________ substage given by Piaget.

A) secondary circular reactions
B) simple reflexes
C) internalization of schemes
D) first habits and primary circular reactions