Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: It is not included among the lipids found in biological membranes: 
 Options:  <1> Isopentenyl pyrophosphate. <2> Phosphatidylinositol. <3> Sphingomyelin <4> Phosphatidic acid. <5> Phosphatidylethanolamine.
