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: Liquid chromatography in normal phase:
Options: <1> It uses a column with apolar groups that interact with the apolar part of the analytes differentially. <2> It is a mode of operation that employs a polar stationary phase with a low polarity mobile phase. <3> It uses highly polar mobile phases such as alkanes or chloroalkanes. <4> It is a mode of operation that employs a non-polar surface with a mixed aqueous / organic mobile phase. <5> It uses stationary phases with a large number of hydrophobic alkyl ligands.
Output:
2