Carbon credits are used to a rehabilitate tropical rainforests
b. reduce the emission of volatile organic compounds (VOC's)
c. regulate how much carbon dioxide a country can emit
d. coordinate carbon sequestration activities

a. by using fur or clothes to trap heat energy near the body

you can have just about every answer you can think of

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.