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: Burkitt's lymphoma and nasopharyngeal carcinoma are related to infection by: 
 Options:  <1> Herpes human virus type 6. <2> Cytomegalovirus. <3> Respiratory syncytial virus. <4> Epstein-Barr virus. <5> HIV.
