Both cellular respiration and photosynthesis rely on electron transport chains embedded in membranes to produce ATP molecules. Which of the following correctly describes the difference between the two types of electron transport chains?

a. in cellular respiration the electron source is water and the final electron destination is oxygen.

b. in cellular respiration the electron source is the hydrogens in energy rich food and the final electron destination is oxygen.

c. in photosynthesis the electron source is water and the final destination is oxygen.

d. both b and c.