Final answer:
The 3 fundamental features of adult attachment are secure, avoidant, and resistant attachment.
Step-by-step explanation:
Secure attachment is the healthiest type and is characterized by a strong bond between the individual and their caregiver. The individual feels safe exploring their environment and seeks out their caregiver in times of stress. Avoidant attachment is when the individual is unresponsive to their caregiver, does not use them as a secure base, and does not care if they leave. Lastly, resistant attachment is when the individual is unsure and inconsistent in their behavior towards their caregiver, displaying both desire for and resistance to their presence.