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

The endoplasmic reticulum (ER) is the main organelle involved in the modification and routing of newly synthesized proteins to their destinations. The ER is a network of membranous tubules and cisternae that is responsible for the synthesis, folding, and transport of proteins. So, the correct answer is the endoplasmic reticulum. Notice that mitochondria are involved in energy production, lysosomes are involved in digestion and recycling, and chloroplasts are involved in photosynthesis. Therefore, options A, C, and D are incorrect.