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: In the treatment with progestogens, a significant number of adverse effects occur. Of those listed below, the most serious is:
Options: <1> Liver failure. <2> Thromboembolic disease. <3> Respiratory insufficiency. <4> Depression. <5> Heart failure.
Output:
2