Choice "C" is correct. The control environment reflects the overall attitude, awareness and actions of those charged with governance (i.e., the board of directors, management, owners, and others) concerning the importance of control and its emphasis in the entity.
Choice "a" is incorrect. Computer-based controls are a control activity. The overall attitude and awareness of those charged with governance is not a control activity.
Choice "b" is incorrect. A system of segregation of duties is a control activity. The overall attitude and awareness of those charged with governance is not a control activity.
Choice "d" is incorrect. Safeguards over access to assets is a control activity. The overall attitude and awareness of those charged with governance is not a control activity.