Which of the following is true regarding the long-term stability of temperament?
Select one:
a. Temperament remains stable through the age of 2 years, but then it becomes unpredictable.
b. The research data varies greatly so we can't draw any reliable conclusions on the longevity of temperament.
c. Difficult children tend to demonstrate the greatest level of instability in temperament.
d. Most studies have found that the basic temperament of a child stays relatively stable at least through age 12.