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: The feet of the following are an integral part of the blood-brain barrier: 
 Options:  <1> Astrocytes <2> Timocytes. <3> Podocytes <4> Ependymal cells. <5> Oligodendrocytes
