Final answer:
The development of a child's positive internal working model is the outcome of having a secure attachment with a caregiver, which is essential for healthy psychosocial development according to John Bowlby's attachment theory.
Step-by-step explanation:
A secure attachment between a caregiver and a child as described in John Bowlby's attachment theory is essential for the child's healthy social and emotional development. A secure attachment is characterized by a caregiver who is responsive to the child's needs and engages in mutually enjoyable interactions with the child. This type of attachment helps develop a child's positive internal working model, which influences their feelings of security and relationships with others throughout their life.
Mary Ainsworth's research, particularly the Strange Situation experiment, built on Bowlby's work to categorize different types of attachment styles. A secure attachment leads to the development of a child's positive internal working model, which impacts their future social interactions and emotional well-being. Relationships with caregivers that are nurturing and responsive foster a secure base from which a child can explore the world and develop positively. Therefore, the correct answer is C) the development of a child's positive internal working model, as it is the element closely related to the concept of secure attachment and reflects the outcome of having such a strong and healthy bond between the caregiver and the child.