Ian and Joshua Are Drug Addicts

Ian and Joshua are drug addicts. At Joshua's request, Ian prepares a syringe of heroin and injects Joshua with it. Joshua dies and Ian is charged with unlawful act manslaughter. According to the Court of Appeal in Cato (1976) , which offence could the prosecutor rely upon as the "unlawful act"?

A) Supplying a controlled drug under the Misuse of Drugs Act 1971
B) Assault occasioning actual bodily harm under s.47, OAPA 1861
C) Maliciously administering a noxious thing so as to endanger life or inflict GBH, contrary to s.23, OAPA 1861
D) Possession of a controlled drug under the Misuse of Drugs Act 1971