A Therapist Has a Goal to Reduce the Mean Number

Multiple Choice

A therapist has a goal to reduce the mean number of patient symptoms expressed for a particular disorder to two symptoms per day.Following therapy,she determines that the z score for 2 symptoms per day is 0.Assuming the data are normally distributed,did she reach her goal?

A) No, because the z score indicates 0 improvement.
B) No, because the z score is not negative (indicating a reduction in symptoms) .
C) Yes; in fact, she actually reduced the mean number of symptoms to 0.
D) Yes, because a z score of 0 is the average, or mean.