Which of the following is the correct net reaction for the combined reaction of glutamine synthetase and glutamate synthase?
a) Glutamine + α-ketoglutarate + NH₄+ → Glutamate + NADP+ + Pi + H₂O
b) Glutamate + ATP + NH₃ → Glutamine + ADP + Pi
c) Glutamate + NH₃ + NADPH → Glutamine + NADP+ + H₂O
d) Glutamine + NADPH + α-ketoglutarate → Glutamate + NADP+ + H₂O