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: In consecutive reactions of first order, the global kinetic constant:
Options: <1> Presents units of concentration-1 time-1. <2> Presents units of time-1. <3> Equivalent to the ratio of the kinetic constants of each stage. <4> Corresponds to the sum of the kinetic constants of each stage. <5> Equivalent to the product of the kinetic constants of each stage.
Output:
2