Research on the Transtheoretical Model Has Indicated That ________

Research on the transtheoretical model has indicated that ________.

A) there is little or no support for the validity of this model
B) people tend to change their behaviours after going through only one cycle of the stages
C) people only move forward through the stages as they change their behaviours
D) people tend to move forward and backward through the stages as they change their behaviours