Answer:
a. Staffing the organization, building core competencies, and structuring the organization and work effort
Explanation:
Staffing is the management function undertaken with an objective to hire right people for the most suitable job position, and keeping filled organizational positions throughout.
A core competency refers to those unique capabilities an organization builds over time owing to innovation, creativity or efficient resource management, which yields competitive advantage to the organization. A core competency cannot be easily imitated by the rival firms and provides competitive edge to the firm who possesses it.
Organizational structure would define the hierarchy and define reporting responsibilities of it's employees, the extent of delegation of tasks and the organizational culture.
Thus for an organization to be capable of executing good strategy, the above three are a requisite.