Employees at Southwest Airlines have highly flexible job descriptions that enable them to chip in and help where needed. Employees are encouraged to help solve problems where they see them. Thus, it's not uncommon to see a Southwest manager helping move passenger luggage into aircraft or check in passengers at a gate. This demonstrates the concepts in

a$.$ Theory $x.$

b$.$ Theory $Y.$

c$.$ contingency theory.

d$.$ management science theory.

e$.$ organizational environment theory.