What Has Research on the Relationship Between Schizophrenia and Cannabis

What has research on the relationship between schizophrenia and cannabis demonstrated?

A) Certain genes may act as vulnerability factors that interact with specific environmental pathogens and can lead to the development of schizophrenia.
B) Cannabis use in youth is an established but weak risk factor for developing schizophrenia.
C) If predisposed to psychosis, smoking cannabis can decrease symptoms.
D) If smoking cannabis induces psychosis, we can use this as proof a marker for schizophrenia.