The answer is D. Carbon cycle
Your answer is C lithosphere because the availability of phosphorus is different than that of carbon and nitrogen because it is found mostly at the lithosphere.
<u>Answer</u>:
Option B. a positive feedback loop
<u>Explanation</u>:
This happens when the product of the reaction is more than that of the reaction. In homeostasis this type of positive feedback loop that can move away. It exacerbates the effect of small disturbance. It also strengthens the change in physiological condition body rather than reversing the change. A slight change in the normal range will result in greater change, and hence the system diverts more from the normal range. It can only be considered normal with definite end point.
Sometimes a single gene can influence many traits is the correct answer