One Should Be Cautious When Examining Instances of Schizophrenia Using

One should be cautious when examining instances of schizophrenia using hospital records from much of the twentieth century because:

A) very few records were kept about diagnostic labels back then.
B) most residents of mental hospitals back then also had depression.
C) many people with psychotic symptoms were misdiagnosed as having schizophrenia.
D) people often faked having schizophrenic symptoms to receive treatment for some other disorder.