In the context of the $\text{Z}$-scheme of photosynthesis, which component is responsible for the transfer of electrons from the cytochrome ${\text{b}}_6\text{f}$ complex to Photosystem $\text{I}$?

Solution

1. Electrons move from $\text{PSII}$ to the cytochrome ${\text{b}}_6\text{f}$ complex via plastoquinone.
2. The cytochrome ${\text{b}}_6\text{f}$ complex then transfers electrons to the lumenal side of the thylakoid.
3. Plastocyanin, a mobile copper protein, accepts these electrons and delivers them to $\text{PSI}$.
4. Hence the answer is (C).