Task: Question Answering
Input (English): Question: In studies that use meta-analysis for the systematic review of the results of psychotherapies, which is the most used dependent variable? : 
 Options:  <1> The number of depressive symptoms. <2> The size of the effect. <3> The systematized observation of the therapist. <4> The number of patients that has been cured. <5> The expectations of the patient.
Output (English): 2