Among the given options, the statement that accurately reflects the impact of Dorothea Dix's study of prison conditions is:
She showed that mental illness is treatable.
Dorothea Dix's study of prison conditions in Massachusetts and Europe focused on the deplorable treatment of mentally ill individuals in prisons. She documented the inhumane conditions they faced and advocated for the establishment of specialized mental health institutions. Through her efforts, she raised awareness about the need for proper treatment and care of individuals with mental illnesses, challenging the prevailing belief that they were incurable or inherently dangerous. Her work led to significant reforms in the treatment of mental illness and the establishment of mental asylums in the United States.