(A) similar to the way human beings breathe
- if i break parse this sentence, i am comparing respire to the way human beings breathe (respire -> breathe)
(B) similarly to human beings who are breathing
- incorrect comparison
(C) just like the breathing of human beings
- we are not comparing the breathing of human beings, but how human beings breathe
(D) as human beings when breathing
- awkward phrasing
(E) just as human beings do when they breathe
- close second, this sentence sounds a bit awkward, though
Eek, this sentence makes me think that I am eating fruit when it is still alive!!
I keep toggling between A and E, but I think that <b>A</b> is my final answer.