Which of the following is a sign of life?

The presence of movement is a fundamental sign of life. It indicates that the body is functioning and responding to stimuli, which are essential characteristics of living organisms. In humans, any form of voluntary or involuntary movement suggests that the nervous system is active and that the individual is alive.

Other choices, while they can occur in living beings, do not necessarily indicate the presence of life on their own. Pale skin can be a sign of various conditions, including shock or illness, but it does not confirm life. Unconsciousness signifies a lack of awareness or responsiveness, which does not necessarily imply the absence of life but raises concerns about the person's condition. Unresponsiveness suggests that an individual is not reacting to external stimuli, which can be concerning but also does not rule out the possibility of life—an unresponsive person may still be alive, though their vital signs and consciousness may be impaired. Thus, movement stands out as the clearest and most direct indicator of life.