Depression and Schizophrenia Seem to Appear in All Cultures but Tend

Depression and schizophrenia seem to appear in all cultures but tend to be characterised by different symptoms within individual cultures.For example, depression in Western culture is generally characterised by feelings of guilt and inadequacy, whereas in developing countries it is characterised by physical distress such as fatigue or illness. This is most likely due to

A) genetic differences between individuals living in different cultures.
B) differences in treatment provided in different cultures.
C) reasons that our current methods of study are incapable of understanding.
D) the fact that social and cultural factors influence psychopathology.