what is the single unique characteristic that distinguishes extant birds from other extant vertebrates?

idk what the options are but

these is a strong electrostatic attraction between the ions hence a lot of energy is needed to overcome this attraction

this is why the boiling points are so high

the flagellates share a facultative mutualist association with termites. mutualism is a biological interaction between individuals of different species, where both benefit from each other. this is called cooperation and it differs from other interactions such as cases of exploitation, such as parasitism, predation. in this interaction called association, both species cooperate and benefit.

answerself- groups