Task: Question Answering
Input (English): 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 (English): 2