A malicious insider from the marketing team alters records and transfers company funds to a personal account. Which of the following methods would be the best way to secure company records in the future?

Permission restrictions are the best method because they directly address the problem of an authorized user (the insider) having excessive privileges. By implementing granular permissions, the marketing team member would only have access to the data and functions necessary for their role, preventing them from altering financial records or initiating fund transfers. Hashing ensures data integrity but doesn't prevent unauthorized modifications by an authorized user. Input validation checks the format and range of data entered but doesn't control who can enter or modify data. An Access Control List (ACL) is a mechanism to implement permissions, but "permission restrictions" is the broader and more accurate answer for the method of securing records in this scenario.