During a penetration test, you discovered critical vulnerabilities that must be communicated to the client. Given the sensitivity of the information, which of the following methods should you use to ensure the secure distribution of the report to the client's C-suite and technical staff?
Secure instant messaging application with the file attached
Uploading the report to a common file-sharing website without additional access controls
Encrypted email with a pre-shared key or digital certificates
Standard email with password protection on the report document