The auditor's best course of action is to document the finding and explain the risk of having administrator accounts with inappropriate security settings. This is because the auditor's role is to identify and report the issues, not to fix them or request others to fix them. The auditor should also communicate the impact of the finding, such as the possibility of unauthorized access, data tampering, or denial of service attacks. The auditor should not assume the responsibility of the IT manager or the DBA, who are in charge of changing the security parameters or disabling the accounts. References:
* CISA Review Manual (Digital Version), Chapter 4, Section 4.2.21
* CISA Online Review Course, Domain 1, Module 3, Lesson 32

The best assurance of data integrity after file transfers is hash values. Hash values are unique strings that are generated by applying a mathematical function to the data. Hash values can be used to verify that the data has not been altered or corrupted during the transfer, as any change in the data would result in a different hash value. By comparing the hash values of the source and destination files, one can confirm that the data is identical and intact.
The other options are not as effective as hash values for ensuring data integrity after file transfers. Check digits are digits added to a number to detect errors in data entry or transmission, but they are not reliable for detecting intentional or complex modifications of the data. Monetary unit sampling is a statistical sampling technique used for auditing financial statements, but it is not applicable for verifying data integrity after file transfers. Reasonableness check is a validation method that checks whether the data falls within an expected range or format, but it does not guarantee that the data is accurate or consistent with the source.
References:
* 5: On Windows, how to check that data is unchanged after copying? - Super User
* 6: Data integrity | Cloud Storage Transfer Service Documentation | Google Cloud
* 7: Checking File Integrity - HECC Knowledge Base
* 8: How to setup File Transfer Integrity Checks - Progress.com

Implementing business rules to validate employee data entry is the best way to reduce the likelihood of future occurrences of poor data quality that cause customer complaints about receiving different items from what they ordered on the organization's website. Business rules are logical statements that define the conditions and actions for data validation, such as checking for data completeness, accuracy, consistency, and integrity. Assigning responsibility for improving data quality, investing in additional employee training for data entry, and outsourcing data cleansing activities to reliable third parties are also possible ways to improve data quality, but they are not as effective as implementing business rules to validate employee data entry. References: CISA Review Manual (Digital Version), Chapter 4, Section 4.3.1