What type of protection does S/MIME provide?

S/MIME, which stands for Secure/Multipurpose Internet Mail Extensions, is primarily focused on securing emails through encryption and digital signatures. The correct answer, regarding email content integrity, is significant because S/MIME ensures that the content of an email remains unchanged during transit. It achieves this by using digital signatures, which allow the recipient to verify that the email was not altered after it was sent and that it indeed came from the claimed sender. This capability is essential in preventing tampering and ensuring that the information delivered maintains its original form.

While S/MIME does contribute to user authentication by confirming the identity of the sender through their digital certificate, the key feature emphasized in the question is the integrity of the email content itself. Virus elimination and network security monitoring fall outside the purview of what S/MIME is designed to accomplish, which is specifically focused on the secure transmission of email.