Which process in photosynthesis will be most directly compromised by inhibition of the cytochrome b6f complex?

In photosynthesis, the cytochrome b6f complex functions to mediate the transfer of electrons between the two photosynthetic reaction centers complexes , from Photosystem II o photosystem I, while transferring protons from the chloroplast stroma across the thylakoid membrane into the lumen.

Ithink the answer is d.

Very hard to understand