What Can Be Concluded from the Studies Regarding Rat Learning

What can be concluded from the studies regarding rat learning and brain structure done by Greenough, Withers, and Wallace (1990) ?

A) Early psychological experience has little to do with brain structure or later development of psychopathology.
B) Early psychological experience affects the development of the nervous system and will determine whether the individual will develop a psychological disorder later in life.
C) Early psychological experience affects the development of the nervous system and influences the number of connections between nerve cells.
D) Early psychological experience does not result in physical changes to the nervous system but can still influence whether or not one develops a psychological disorder.