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?
Send the email only when connected to a secure, trusted wireless network.
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.
Trust the security provided by the email service provider's standard encryption protocols in place.