The correct option is A Endoplasmic Reticulum
The process of glycosylation involves the attachment of glycans to the organic molecules like lipids, proteins etc. It is needed for the production of materials for secretion like glycoproteins require glycosylation reaction. As endoplasmic reticulum are the major secretory organelles in the cell. Glycosylation reactions are most prominent in the endoplasmic reticulum.