Final answer:
The nurse is exhibiting the 'assuming the sick role' behavior by calling out due to the flu, which allows exemption from normal duties with the expectation of recovery.
Step-by-step explanation:
The nurse who calls in to report he has the flu and will not be at work is exhibiting behavior that aligns with assuming the sick role. This is the stage in illness behavior where a person acknowledges being ill and therefore exonerates themselves from their usual social roles and responsibilities. According to Talcott Parsons' functionalist perspective, this includes the right to be exempt from normal social roles, but also carries the responsibility to seek help and to try to recover. It is important for a sick person to not prolong this stage unnecessarily, as that could lead to stigmatization, known as malingering. The stage of assuming the sick role is necessary not only for the healing of the individual but also for maintaining the stability of society.