Which of the following statements is true of managerial accounting?

a$.$ Reporting under managerial accounting is constrained by rules such as generally accepted accounting principles.

b$.$ Managerial accounting is required to be reported annually but also may be reported monthly or quarterly.

c$.$ Managerial accounting is primarily concerned with generating information for use by managers.

d$.$ Managerial accounting provides information to the external stakeholders of the company.