For enabling visibility into EVPN-VXLAN network traffic through continuous monitoring:
You must enable sFlow monitoring on each interface individually (Option C): sFlow is a sampling technology used for monitoring network traffic. In a Juniper environment, sFlow needs to be enabled on individual interfaces to start collecting traffic samples. This allows for granular control over which interfaces are monitored.
You cannot enable sFlow monitoring on each interface individually (Option A): This statement is incorrect, contradicting the above explanation. sFlow can and should be enabled on specific interfaces as needed.
The option stating that the sFlow agent needs to be manually installed on QFX Series switches (Option D) is inaccurate, as the sFlow feature is typically integrated into the Junos OS running on QFX Series switches. The statement about the sFlow agent being installed by default on QFX Series switches (Option B) is partially true but does not directly address the question of enabling visibility into network traffic.
Reference
Juniper Networks: Configuring sFlow Technology for Network Monitoring