Which of the following is true concerning the role of redox reactions in photosynthesis and cellular respiration? a. photosynthesis involves only reductions while respiration involves only oxidations

b. photosynthesis involves only oxidations while respiration involves only reductions

c. in photosynthesis, carbon dioxide is oxidized to form sugar while in respiration sugar is reduced to form carbon dioxide

d. in photosynthesis, carbon dioxide is reduced to form sugar while in respiration sugar is oxidized to form carbon dioxide

e. none of the choices are true