The main organelle involved in modification and routing of newly synthesized proteins to their destinations is :

The endoplasmic reticulum (ER) is a type of organelle found in eukaryotic cells that is involved in several processes, including protein synthesis, folding, and transport. The ER comes in two forms: rough ER, which has ribosomes attached to it and is involved in protein synthesis, and smooth ER, which is involved in lipid synthesis and detoxification. After proteins are synthesized by the ribosomes attached to the rough ER, they are inserted into the ER lumen where they can be modified (e.g., by glycosylation) and folded into their native conformation. The ER then transports these proteins to other parts of the cell, such as the Golgi apparatus, lysosomes, or the plasma membrane, or secretes them outside the cell. Therefore, the main organelle involved in the modification and routing of newly synthesized proteins to their destinations is the endoplasmic reticulum. So, the correct answer is option (B) endoplasmic reticulum. Think of it this way: the endoplasmic reticulum acts as a highway system within the cell, directing proteins to where they are needed.