You will be given a definition of a task first, then some input of the task.
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'.

Question: A 55-year-old man, the father of a celiac son, with iron deficiency anemia and a recent increase in the rhythm of deposition, has been determined to have a negative HLA-DQ2 and HLADQ8 allele. Which diagnostic study is the most appropriate in this case?
Options: <1> Determination of IgA anti-transglutaminase antibodies. <2> Upper digestive endoscopy with taking of duodenal biopsies. <3> D-xylose test. <4> Evaluate the response to a gluten-free diet. <5> Colonoscopy
Output:
5