Explanation
The nitrogen base attached to phosphoric acid in phospholipid lecithin is C: Choline.
Lecithin is a phospholipid that consists of a glycerol backbone, two fatty acid chains, a phosphate group, and a nitrogen-containing alcohol. The nitrogen-containing alcohol is either choline or ethanolamine.
In the case of lecithin, the nitrogen base attached to the phosphate group is choline. This makes it a phosphatidylcholine. Ethanolamine can also be attached to the phosphate group in other phospholipids, such as phosphatidylethanolamine.
Sphingosine and cephalin are not directly involved in the structure of lecithin. Sphingosine is a type of long-chain amino alcohol found in sphingolipids, while cephalin is a term used to describe a group of phospholipids that contain ethanolamine or serine as their nitrogen-containing alcohol.
