Hey there!
It looks like we're looking at Erikson's Psychosocial Stages Of Development.
In terms of infancy, we have basic trust versus mistrust.
The baby is looking for who to trust and who to stay by, and more often than not that's no other than his/her's own mother.
In early adulthood, (20-25 years old) we have a different situation.
This is where people start looking at relationships more, and start thinking more about love. Therefore, we have C, intimacy versus isolation.
I hope this helps!
