As a flight attendant on a transatlantic route, Mark Duffy works long and sometimes chaotic hours. Even so, Mark knows that no matter how tired he may feel, part of his job is to greet and smile at passengers as they enter the aircraft and to project an aura of calm competence. Mark's job requires__________.

a. social loafing
b. emotional labor
c. cognitive dissonance
d. self-concordance
e. positivity offset