Nitrogen fixation is a process in which nitrogen (N2) in the Earth's atmosphere is converted into ammonia (NH3). Atmospheric nitrogen or molecular dinitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds.
Humans can will themselves to eat more, as we know that food comes easy to us.
Animals, on the other hand, top priority is survival, so they usually wouldn't think about eating more because it just "tastes good."
B. because it is dependent on something to manipulate (change) it, that is why it is called a dependent variable :)
I really think that its the second one; Nihilist
