The correct answer is Implementing a secrets management solution to centrally manage and securely store sensitive information. It is the most effective recommendation as it suggests a method to encrypt secrets and control access to them, which is essential for maintaining their confidentiality and integrity. Storing secrets in plaintext, as observed in the scenario, poses a significant security risk because if an attacker gains access to these files, they would have immediate access to the sensitive data. A secrets management solution provides a secure way to manage access to secrets, often including rotation and auditing capabilities that further enhance security. The incorrect answers fail to address the fundamental issue of securely managing secrets or do not align with best practices for secrets management.