What is the purpose of assigning logical interfaces to separate security zones in Junos OS?

In Junos OS, security zones are the foundation of SRX firewall policy enforcement. Logical interfaces must be assigned to zones. This enables:

Separation of traffic by zone boundaries.

Enforcement ofsecurity policiesfor traffic traversing between zones.

Control of traffic across VLANs, subnets, or functional areas (e.g., trust, untrust, DMZ).

Other options:

Zone assignment is not used to simplify interface configuration (A).

Routing protocols and updates (B) are handled by routing instances, not zones.

SNMP monitoring (D) is enabled under system or services configuration, not zones.