(N/A) In cyclic photophosphorylation,the process is restricted to Photosystem $-I$ $(PS-I)$. When the reaction center,Chlorophyll $P_{700}$,absorbs light,it becomes excited and emits electrons. These electrons are captured by an electron acceptor and then passed through an electron transport system. As the electrons move through the transport system,energy is released,which is used to synthesize $ATP$ from $ADP$ and inorganic phosphate $(iP)$. Finally,the electrons are returned to the reaction center,Chlorophyll $P_{700}$,completing the cycle. Thus,the missing labels are 'Light' for the circle,'e$^-$ acceptor' for the top oval,and '$P_{700}$' for the bottom oval.