In which organ does the majority of photosynthesis take place

The term "organs" applies mostly for complex organism such as mammals. The term used in organisms that perform photosynthesis [Plants] is organelle.
The organelle where photosynthesis takes place is the chloroplast. Most chloroplasts are found in the leaves. In the leaves is where most photosynthesis occurs.

The organelle where photosynthesis takes place are the chloroplasts, as they contain the chlorophyll pigment

Bidk

The answer is energy. the arrows are showing how exited and energized the stones are.