Task: Question Answering
Input (English): Question: In a determination of the activity of an enzyme, the depletion of the substrate: 
 Options:  <1> It is essential for most trials. <2> It may give falsely low results in sera with high enzymatic activity. <3> It occurs when the reagent is finished. <4> It occurs due to a defect in the spectrophotometer. <5> It can lead to falsely elevated results in sera with high enzymatic activity.
Output (English): 2