What is cholesterol among the following?

Cholesterol is a steroid, a type of lipid (fat) that is found in all cells of the body. It is crucial for the production of cell membranes, hormones, and vitamin D. Cholesterol is categorized into two types based on its density: 1. Low-Density Lipoprotein (LDL) - Often referred to as "bad" cholesterol because it can build up on the walls of arteries. 2. High-Density Lipoprotein (HDL) - Known as "good" cholesterol because it helps remove LDL from the bloodstream. Thus, the correct answer is (a), Steroid.