The correct option is:**(a) PS I**
Explanation:
Cyclic photophosphorylation is a process of photophosphorylation in which an electron expelled by the excited photocentre is returned to it after passing through a series of electron carriers. Cyclic photophosphorylation is performed by photosystem I only. The electron is circulated within the photosystem and the phosphorylation occurs due to cyclic flow of electron. The excited electron does not pass on to NADP but is cycled back to the PS I compiler through the electron transport chain. The cyclic flow hence, results only in the synthesis of ATP, but not of NADPH + H+ .
