14. amphibians have adapted to the challenge of distributing oxygen more
efficiently to all cells by
a. developing a double-loop circulatory system
b. breathing more quickly
c. breathing only out of water
d. developing a one-way respiratory system

Amphibians have adapted to the challenge of distributing oxygen more

efficiently to all cells by  developing a double-loop circulatory system. Hope that helps! :)

preservation because he preserves part of the land and preserves means save

explanation:

the answer is cell division : )