Final answer:
The answer to the student's question is B. Sphingosine; ceramide. Sphingosine is the 18 carbon amino alcohol found in sphingolipids, and when combined with a fatty acid, it forms ceramide.
Step-by-step explanation:
All sphingomyelin has an 18 carbon amino alcohol derivative called sphingosine, which when attached to a fatty acid is called ceramide.
This means the correct answer to the student's question is B. Sphingosine; ceramide. Sphingosine is the alcohol backbone found in all sphingolipids, and when it is attached to a fatty acid via an amide bond, it forms ceramide. Ceramide is a key intermediate in the biosynthesis of complex sphingolipids, including sphingomyelin, which is a type of sphingophospholipid containing a fatty acid, phosphoric acid, sphingosine, and a choline unit.