In the diagram shown below label A, B, C

In the diagram shown below label A, B, C. What type of phosphorylation is possible in this?

If is the process called cyclic photophosphorylation. Here, A is electron acceptor, B is electron transport system and C is chlorophyll ${ P }_{ 700 }$.
In cyclic photophosporylation, only PS-I is functional. The electron is circulated within the photosystem and the phosphorylation occurs due to cyclic flow of electrons.