Final answer:
Option C. Emergency or involuntary admission may be necessary for an individual who exhibits harmful behavior, such as throwing a heavy plate at a waiter due to command hallucinations, as this can indicate a severe psychotic episode requiring immediate attention.
Step-by-step explanation:
An individual diagnosed with mental illness may require emergency or involuntary admission if they pose a threat to themselves or others due to the severity of their condition. Among the scenarios provided, the individual who throws a heavy plate at a waiter at the direction of command hallucinations is exhibiting dangerous behavior and may need such an admission.
This behavior can be indicative of a severe psychotic episode, possibly due to an underlying mental illness such as schizophrenia, where the individual is not able to distinguish between reality and their delusions or hallucinations, leading to potentially harmful actions prompted by these false perceptions.
The use of heroin while on naltrexone, hearing angels during thunderstorms, or not keeping a mental health appointment, while concerning, may not meet the criteria for emergency admission unless they are associated with immediate risk of harm to the individual or others. In any case of substance use disorder or mental illness, a complete assessment by a healthcare professional is needed to determine the best course of treatment.