Cyclic photophosphorylation involves:

Explanation

Cyclic photophosphorylation involves only Photosystem I (PS I). In this process, electrons are transferred cyclically back to the PS I reaction center, allowing for the production of ATP without the generation of NADPH. This contrasts with non-cyclic photophosphorylation, which involves both PS I and PS II and leads to the production of both ATP and NADPH. Options B, C, and D are incorrect because they involve elements not part of the cyclic photophosphorylation pathway: PS II is not involved (hence options B and C are wrong), and P680 is a component of PS II, not PS I (hence option D is wrong).