Answer:
b. narcissistic personality disorder
Explanation:
In 1900, communicable diseases, like pneumonia, TB, influenza, chicken pox, and polio, were the most common causes of death. However, with the development of medicine, and vaccines, now In 2006, lifestyle diseases, like cancer, heart disease, and stroke, were the most common causes of death.
The control group is usually the group in which none of their variables are changed. This group is used in order to compare it with the outcomes of the other groups.
