Biology

The correct answer is: D.Lipid.

The smooth endoplasmic reticulum (SER) is primarily involved in the synthesis of lipids, including phospholipids and steroids. It also plays a role in the metabolism of carbohydrates and detoxification of drugs and poisons, but its main function is lipid production.

Here’s a breakdown of the options:

A.Nucleic acid: Nucleic acids (DNA and RNA) are not produced by the SER; this occurs in the nucleus and nucleolus.