The correct option is A Isolated areas on chloroplast lamellae where photosynthetic units exist
Quantasome is a particle that is embedded in a paracrystalline array on the surface of thylakoid discs in chloroplasts. Quantasomes are composed equally of lipids and proteins, which include various photosynthetic pigments and redox carriers. For this reason they are considered to be photosynthetic units. Quantasomes are isolated areas on chloroplast lamillae where photosynthetic units exists. Thus, option A is correct.
Quantasomes are not related to mitochondria and lysosomes. Thus, other options are incorrect.