B. Mitochondria
The process of cellular respiration is essentially when oxygen and carbon transfuse themselves together to create carb on dioxide, which in turns creates energy.
The entire process is formed in the powerhouse of the cell, or in other words, the mitochondria.
A part of this question that may have been confusing is the answer, "lungs". Since respiration is correlated to the lungs, you may have been confused. However, this is a process that occurs within your cells, so on a small scale than your entire body.
Answer:
An ecological pyramid is a pyramid that illustrates the relations between living organisms at different levels
Punnet square
Let's call black 'B' and white 'b'
Being intermediate, gray cats will have the alleles 'Bb'
Being recessive, white cats will have the alleles 'bb'
<u> Gray </u>
|<u> </u>|<u> B | b |</u>
White |b|<u> Bb | bb|</u>
|b|<u> Bb | bb|
</u>
^Apologies for the awful drawing XD
Bb = Gray
bb = White
So the cats can have gray or white fur (A)