Final answer:
The absence of normal behavior like lack of emotion, speech, and extreme apathy is often associated with severe mental health disorders and is closest to 'lack of interest in everything.' Seeking professional help is crucial for a proper diagnosis and treatment.
Step-by-step explanation:
The absence of normal behavior such as the lack of emotion, a complete lack of speech, and extreme apathy are commonly referred to as symptoms associated with certain mental health disorders. These symptoms can sometimes be observed in individuals with conditions like severe depression, schizophrenia, or after taking certain neuroleptic drugs.
They may manifest as a diminished emotional response, lack of motivation or interest in activities, and impaired communication abilities. It is important to seek professional help if someone is exhibiting these types of behaviors, as they can significantly affect an individual's quality of life.
From the provided options, the closest term that describes the absence of normal behavior would be 'b. Lack of interest in everything.' However, it's important to note that a professional diagnosis by a qualified mental health practitioner is essential, as these symptoms can be complex and may overlap with a variety of mental health issues.