A major department store chain has a strict policy of banning photographs or videos of its sales floor or back$-$room operations. It also does not allow academies to conduct studies of it for pablication in research journals. In fact, some of its own top managers refer to the management's policies on secrecy as "verging on paranoid." These policies indicate that the top management of the firm believes the organization's core competencies are:

a$.$ common.

b$.$ imitable.

c$.$ unobservable

d$.$ causally ambiguous.