<span>A.) vascular ....,,,,</span>
Oxygen
Oxygen is the final electron acceptor, no part of the process - from the Krebs Cycle through the electron transport chain- can happen without oxygen. Aerobic respiration is complete
I think the answer MIGHT be D. RNA synthesis is carried out by proteins known as RNA polymerases that transcribe the genetic information from DNA in a highly-regulated, multi-stage process. But transcribe and translate are different so I'm not a 100% sure. Hope this helps!
The body contains about a trillion cells
