Answer:
Chloroplast: "The organelle which act as the main location or spot for driving the process of photosynthesis inside plants and in the eukaryotic algae."
Grana: Inside the chloroplast's membrane there are certain coin like structures which are placed one over the other for driving the process of photosynthesis inside the plants and the eukaryotic algae. The coin like structure which makes up a single Grana inside the organelle are called as the thylakoids. As many thylakoids are assembled upon one another and forms a more systematic order to form a structure know as the grana.
Granum: When more then one grana are connected to each other
through the stroma thylakoids, acting as a bridge between the different structures. The thylakoids provides more surface or area for the light reactions to take place.