Which Statement Best Describes the Emergence of Schizophrenia and the Use

Which statement best describes the emergence of schizophrenia and the use of psychoactive substances

A)  They are completed unrelated. 
B)  Research suggests a causal link between marijuana use and the onset of schizophrenia, although the reasons why are not fully understood. 
C)  There is no evidence that methamphetamines contribute to the emergence of schizophrenia. 
D)  Neither marijuana nor methamphetamines have been associated with an increased risk of onset of schizophrenia.