Which of the following conditions is characterized by a prolonged immobility and unresponsiveness?

Catatonia is characterized by a state where an individual may exhibit prolonged immobility and unresponsiveness, which reflects a significant decrease in movement and lack of reaction to the environment. In this state, a person can appear to be in a trance-like condition, often remaining in the same posture for extended periods and showing minimal spontaneous activity.

Patients with catatonia may also display odd behaviors, such as stereotyped movements or even purposeless gestures, but the key defining feature is the combination of unresponsiveness and reduced mobility. This condition can be associated with various underlying psychiatric or medical issues, ranging from mood disorders to schizophrenia.

In contrast, stupor involves a state of near-unconsciousness with minimal response to stimuli, but typically does not have the same extent of immobility as catatonia. Somnolence refers to a state of drowsiness or sleepiness, while confusion involves disorientation and difficulty in understanding one's surroundings without the immobility characteristic of catatonia. Thus, catatonia is the most accurate term for the described condition of prolonged immobility and unresponsiveness.