The correct option is A Grana
Photosynthesis occurs in two stages- light reaction and dark reaction. The light reaction precedes dark reaction and produces the reducing power and assimilatory power which are used up subsequently in dark reaction. The light reaction occurs in thylakoid lamellae organised into grana and the dark reaction occurs in the stroma of the chloroplast. The light reaction is carried out by the two photosystems. The photosystem II is localized in grana.