Which of the following statements about managerial accounting is true? a. Managerial accounting is mainly used to generate financial information for external parties. b. Under managerial accounting, transactions and events are required to be recorded and reported using generally accepted accounting principles (GAAP). c. Reports generated using managerial accounting are required to be reported annually but may be reported monthly or quarterly. d. Under managerial accounting, reports are prepared as needed by management for its decision making