How does Cisco IOS server load balancing (SLB) enhance security of a real server?

How does Cisco IOS server load balancing (SLB) enhance security of a real server?

• The IP address of the real server is not needed with IOS SLB, which relies only on MAC addresses.
• The IP address of the real server is translated with Network Address Translation (NAT).
• The IP address of the real server is advertised as part of a distinct network.
• The IP address of the real server is never announced to the external network.

Exam with this question: CCNP SWITCH (Version 6.0) Chapter 5 Exam