Which of the following procedures can organizations use to address credit risk most effectively?

a. An informal credit policy, which may be automated for most transactions but requires special approval for large and/or unusual transactions. 

b. A periodic review of the credit policy by key executives to determine whether changes are dictated either by current economic events or by deterioration of the receivables.

c. Periodic monitoring of receivables for evidence of increased risk, such as increases in the number of days past due or an unusually high concentration in a few key customers whose financial prospects are declining.

d. Adequate segregation of duties over fixed assets, with specific authorization to write off fixed assets that have been fully depreciated.