Terminal bronchioles eventually terminate in:
a) alveoli
b) bronchioles
c) main (primary) bronchi
d) glottis
e) diaphragm

A) alveoli

Explanation:

Bronchioles are part of the respiratory system by which air passes from the nose  to the alveoli (air sacs). They are divided  into smaller terminal bronchioles which are  the conducting zone (involved in respiration) and these then divide into the smaller respiratory bronchioles - the beginning of the respiratory region. Terminal bronchioles are the most distant segment of bronchioles which divide to form respiratory bronchioles which contain a small number of alveoli.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.