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: The antiulcer drug called omeprazole has in its structure:
Options: <1> A benzimidazole heterocycle. <2> A thiol group. <3> A pyrazole heterocycle. <4> A dimethylamino group. <5> A thiozolic heterocycle.
Output:
1