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: Circadian rhythms are established in: 
 Options:  <1> Pineal gland. <2> Suprachiasmatic nucleus. <3> Retina. <4> Spinal cord. <5> Centromedianic thalamic nucleus.
