During the light reactions, H⁺ accumulates in the
- A
Outer chloroplast envelope
- Bcheck_circle
Thylakoid lumen
- C
Stroma
- D
Cytoplasm
Explanation
Both water-splitting (releases H⁺ into the lumen) and the cytochrome complex (pumps H⁺ from stroma to lumen) build a proton gradient used by ATP synthase.