An employee needs to transmit sensitive client data to a colleague at another branch. Out of the following methods, which is the MOST secure for preventing unauthorized access during transmission?
Trust the security provided by the email service provider's standard encryption protocols in place.
Use digital signatures and encrypt the email using end-to-end encryption methods like PGP (Pretty Good Privacy) or S/MIME (Secure/Multipurpose Internet Mail Extensions).
Place the sensitive data in a password-protected ZIP file before emailing it to the colleague.
Send the email only when connected to a secure, trusted wireless network.