According to Freud, What Is the Basis for the Development

According to Freud, what is the basis for the development of attachment?

A) pleasure derived from oral activities such as sucking and feeding
B) the mother acting as a conditioned stimulus for positive outcomes
C) the maturing of the infant's concept of object permanence
D) preprogrammed responses (such as smiling, crawling, and vocalizing) that help to initiate or maintain contact