What is the relationship between family dysfunction and schizophrenia?

A. Family dysfunction is a major causative factor for schizophrenia.

B. Family dysfunction plays a minor role in developing schizophrenia.

C. Research has failed to substantiate a direct causal link between family dysfunction and schizophrenia.

D. Research has substantiated a link between family dysfunction and schizophrenia but can't say which causes the other.