The correct option is A Nucleolus
Nucleolus is a non-membrane bound, spherical structure present inside the nucleus. It is a site for the biosynthesis of ribosomal RNA (rRNA). rRNA is a major component of ribosomes which are sites of protein synthesis. Hence, numerous large nucleoli are present in cells actively involved in protein synthesis.
Golgi apparatus - site for the synthesis of glycoproteins and glycolipids.
Microbodies (Peroxisomes, glyoxysomes, etc.) - They contain enzymes and are involved in a variety of metabolic reactions.