2017 exam question

[Anne Boleyn]

hey guys can someone please explain this question:
Question 11
An animal cell culture was exposed to radioactively labelled oxygen. The cells were then monitored for three minutes.
After this time, the radioactively labelled oxygen atoms would be present in which cellular chemical?
A. adenosine triphosphate
B. carbon dioxide
C.    glucose
D.    water                           thanks in advance

[darkz]

Well oxygen acts as the final electron acceptor in the electron transport chain to form water. Therefore the answer is H2O