Metabolism of lipids occurs in:

Explanation

Lipid metabolism primarily occurs in the Smooth endoplasmic reticulum (SER) of cells. The SER is involved in the synthesis of various lipids, such as phospholipids, which are essential components of cell membranes. It is also responsible for the synthesis of lipoproteins, which transport lipids throughout the body. Additionally, the SER is involved in the breakdown (catabolism) of certain lipids, such as triglycerides, through a process called lipolysis. The nucleus (option A) is not directly involved in lipid metabolism. The nucleus contains the cell's genetic material (DNA) and is primarily responsible for gene expression and regulation. The Golgi complex (option B) is involved in modifying, sorting, and packaging lipids and proteins produced in the ER. While it plays a role in lipid metabolism indirectly, the primary site for lipid metabolism is the rough ER. Option C ("None") is incorrect because lipid metabolism does occur in cells, albeit predominantly in the rough endoplasmic reticulum.