Question: In a 5G System's PLMN Interconnection scenario, where there is no IPX between Security Edge Protection Proxies (SEPPs) and only IP routing service is offered without content modification or observation, which security protocol is mandated for use in conjunction with the specified transport protocol?
Option 1: Transport Layer Security (TLS)
Option 2: Network Domain Security/Internet Protocol (NDS/IP)
Option 3: Secure Sockets Layer (SSL)
Option 4: Internet Protocol Security (IPSec)
Explanation: According to the specified transport protocol requirements, when there's no IPX between SEPPs or if IPX only offers routing without modifying/observing content, TLS is mandated for security protection. This ensures secure communication over the Transmission Control Protocol (TCP), which is used as the transport protocol due to HTTP/2 requirements.