Which is the most appropriate statement?

Risk assessment has been described by COSO as

a. Every entity faces a variety of risks from internal sources that must be assessed. A precondition to risk assessment is establishment of objectives, linked at different levels and internally consistent.

b. Every entity faces a variety of risks from external sources that must be assessed. A precondition to risk assessment is establishment of objectives, linked at different levels and internally consistent.

c. Every entity faces a variety of risks from external and internal sources that must be assessed. A precondition to risk assessment is establishment of objectives, linked at different levels and internally and externally consistent.

d. Every entity faces a variety of risks from external and internal sources that must be assessed. A precondition to risk assessment is establishment of objectives, linked at different levels and internally consistent.