Explanation:

Photosynthesis:
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. It involves several complex reactions that take place in the chloroplasts of plant cells.

Electron Transfer in Photosynthesis:
During photosynthesis, electron transfer occurs in two main processes: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle).

1. Light-Dependent Reactions:
These reactions occur in the thylakoid membrane of the chloroplasts and involve the absorption of light energy by the pigment chlorophyll. The light energy is used to excite electrons, which are then transferred through a series of electron carriers.

- Pheophytin:
Pheophytin is a chlorophyll molecule that acts as the primary electron acceptor in Photosystem II (PSII) during the light-dependent reactions. It accepts electrons from chlorophyll molecules that have been excited by light absorption.

- Cytochrome-b:
Cytochrome-b is not directly involved in the electron transfer during photosynthesis. It is a component of the electron transport chain found in the inner mitochondrial membrane of eukaryotic cells. In photosynthesis, cytochrome-b is not a part of the electron transport chain in the thylakoid membrane.

- Plastocyanin:
Plastocyanin is a copper-containing protein found in the thylakoid lumen. It acts as a mobile electron carrier between the cytochrome b6f complex and Photosystem I (PSI) during the light-dependent reactions. Plastocyanin transfers electrons from the cytochrome b6f complex to PSI.

- Cytochrome-a:
Cytochrome-a is another component of the electron transport chain found in the inner mitochondrial membrane. Similar to cytochrome-b, it is not directly involved in the electron transfer during photosynthesis.

Therefore, the compound that does not involve in the electron transfer in photosynthesis is cytochrome-b (Option B).