Instructions: 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: What pair of modified amino acids is very common in collagen?
Options: <1> 4-Hydroxy-proline and 5-Hydroxy-lysine. <2> Histamine and 5-Methyl-lysine. <3> Carboxyglutamate and 4-Hydroxy-proline. <4> S-Adenosyl-methionine and 5-Methyl-proline. <5> Methyl-Phenylalanine and Histamine.
Output:
1