<span> It is called the Calvin Benison Cycle</span>
The answer is A
This is because 90% of energy is lost when we go up one trophic level. This means that even the the consumers tend to be larger in size, they are fewer in number and need to eat more in order to sustain themselves.
<span>(decreased variation in tail feather color because no form of the trait is advantageous) Due to the fact that the tail color is no longer a necessity, so it will eventually stop being needed and variation will decrease.</span>
I think the answer is evolution.