Compare the role of the electrons in the three electron transfer cycles (PSII, PSI, and aerobic respiration) where they originate and what is produced by them as they move through the ETC?

the answer is c

explanation:

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

i am sorry but i need more information and a picture.