I believe the correct answer is secure babies.
The attachment in early years of development is truly important and influential on later character development. Psychologists concluded that there are four types of attachment that might be developed in early years between parent and a baby: secure, avoidant, ambivalent and disorganized-disoriented. Psychologist Mary Ainsworth devised the “Strange Situation” experiment to assess the quality of an infant's attachment to the care giver. This experiment showed that babies with secure attachment to their care giver would cry when their mother left the room but were happy upon her return.