Photophosphorylation occur in light reaction. This takes place in the thylakoid membrane. The photosystem I and II that involves the electron carriers; are present in the thylakoid membranes of the chloroplast. So, option d is correct.

Thylakoid Membranes: The Site of Photophosphorylation

Photophosphorylation is the process by which ATP is synthesized using light energy during photosynthesis. It occurs in the thylakoid membranes of the chloroplasts. The thylakoid membranes are specialized structures within the chloroplasts that contain the photosystems and electron transport chains necessary for capturing light energy and generating ATP.

Electron Carriers Involved in Photophosphorylation

The electron carriers involved in photophosphorylation are located in the thylakoid membranes. These electron carriers play a crucial role in the flow of electrons during the light-dependent reactions of photosynthesis. They include:

1. Photosystem II (PSII): PSII is located in the thylakoid membranes and is responsible for capturing light energy and initiating the electron transport chain. It consists of a reaction center containing chlorophyll a molecules and accessory pigments. When light is absorbed by the pigments, it excites electrons, which are then transferred to the primary electron acceptor of PSII.

2. Plastoquinone (PQ): Plastoquinone is a mobile electron carrier that is embedded in the thylakoid membrane. It accepts electrons from the primary electron acceptor of PSII and transfers them to the cytochrome b6f complex.

3. Cytochrome b6f complex: This complex is also located in the thylakoid membrane and is involved in the transfer of electrons between the two photosystems (PSII and PSI). It pumps protons across the thylakoid membrane, creating a proton gradient that drives ATP synthesis.

4. Plastocyanin (PC): Plastocyanin is a small copper-containing protein that shuttles electrons between the cytochrome b6f complex and PSI. It transfers electrons from the cytochrome b6f complex to the reaction center of PSI.

5. Photosystem I (PSI): PSI is another photosystem located in the thylakoid membrane. It absorbs light energy and transfers electrons to a ferredoxin (Fd) protein.

6. Ferredoxin (Fd): Fd is an iron-sulfur protein that accepts electrons from PSI and transfers them to the enzyme NADP+ reductase.

7. NADP+ reductase: This enzyme catalyzes the final step of photophosphorylation, which is the reduction of NADP+ to NADPH. NADPH is an important reducing agent used in the Calvin cycle for the synthesis of carbohydrates.

In conclusion, the electron carriers involved in photophosphorylation are located in the thylakoid membranes of the chloroplasts. These carriers, including PSII, PQ, the cytochrome b6f complex, PC, PSI, Fd, and NADP+ reductase, work together to capture light energy, generate a proton gradient, and produce ATP and NADPH for the Calvin cycle.