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: Which of the following reliability calculation methods can not be carried out with a single application of the test?
Options: <1> Alpha coefficient of Cronbach. <2> Guttman-Flanagan. <3> Rulon <4> Method of parallel forms. <5> Method of the two halves.
Output:
4