I'm not completely sure but I came up with Carbon dioxide, methane, water vapor, and nitrous oxide. I hope this is right and maybe helps you. Good luck!!
Answer:
the answer is D :)
Explanation:
Active transport uses energy molecules to move particles like sodium, against their concentration gradients, from areas of low concentration to areas of high concentration.
Environmental scientists are using GPS ( It is effective but expensive) aerial monitoring (Quick but not the easiest), RFID tags, (mostly for long-term monitoring) and hidden cameras are used to study polar bear behavior without interruption to their environment.