Which of the following CNS depressants are used in maximum for suicidal purposes?

Opium is selected for suicides because death is painless. It is rarely used for homicide because of its bitter taste, characteristic smell and colour. Poisoning may occur in addicts. Drugging of children by opium to keep them quiet, and overdosage of medicines containing opium may result in accidental poisoning. Fatal dose of opium is 2 g; fatal period is 6-12 weeks. Ref: The Essentials of Forensic Medicine and Toxicology by Dr K. S.Narayan Reddy, 27th edition, Page 517.