(d) : Non-cyclic photophosphorylation involves both PS-I and PS-II. Here electrons are not cycled back and are used in the reduction of NADP to NADPH ‌2. The electrons generated by PSII are passed over a series of electron carriers in a downhill journey and handed over to reaction centre of PSI. PSI again passes the electrons to NADP ‌+ which combines with H+ ions to form NADPH.