Final answer:
The Rough Endoplasmic Reticulum is the correct answer as it is covered with ribosomes, synthesizes secreted proteins, and transports them via vesicles while being involved with phospholipids.
Step-by-step explanation:
The organelle described as being covered in ribosomes, involved in the secretion of proteins, and associated with the segregation and transport of proteins via vesicles, which also contains phospholipids, is the Endoplasmic Reticulum (ER), specifically the Rough Endoplasmic Reticulum (Rough ER) due to the presence of ribosomes. It is a critical part of the cell's protein synthesis and transport mechanism. Proteins synthesized in the Rough ER are eventually transported to the Golgi apparatus, where they are further modified, sorted, and tagged for their correct destinations. The rough surface of the Rough ER is due to the presence of ribosomes, which are sites of protein synthesis. These proteins can either be used within the cell or expelled through the process of exocytosis.