Explanation
A risk assessment should be conducted in order to identify the potential risks associated with a particular system or process, and to determine the best way to mitigate those risks. Making a revision to a password policy based on the results of a risk assessment is the best way to ensure that the policy is effective and secure.
According to the Certified Information Security Manager (CISM) Study manual, the BEST justification for making a revision to a password policy is a risk assessment. A risk assessment enables an organization to identify and evaluate the risks to its information assets and determine the appropriate measures to mitigate those risks, including password policies. Password policies should be based on the risks to the organization's information assets and the level of protection needed.