The Effect of a Treatment in a Simple Interrupted Time-Series

The effect of a treatment in a simple interrupted time-series design is indicated by

A) a clear discontinuity (abrupt increase or decrease) in the dependent variable at the point the treatment is administered.
B) a decreasing trend in the dependent variable that is present both before and after the treatment.
C) an increasing trend in the dependent variable that is present both before and after the treatment.
D) a gradual change in the dependent variable that begins just before the treatment is implementeD.