Which of the following hypotheses are contingency theories? Check all that apply.

a) People with a high need for achievement are motivated by difficult tasks, while people with a low need for achievement are motivated by easy tasks.

b) Managers in customer service environments must spend more time with employees than managers in manufacturing environments in order to be equally successful.

c) Organizations in turbulent environments function more effectively than those in stable environments.

d) Companies where work is highly specialized are more effective than companies where work is not specialized.

e) Decentralized organizations are more effective than centralized organizations.