Question: What is the primary purpose of an NF Service Consumer including an `If-None-Match` header with entity tags in a conditional GET request to the NRF (Network Function Repository)?
Option 1: To authenticate the NF Service Consumer for access to the NRF.
Option 2: To specify the preferred communication protocol version for the interaction.
Option 3: To instruct the NRF to return the requested resource only if it has been modified since the entity tag was last received.
Option 4: To request a list of all available network functions from the NRF.
Explanation: The `If-None-Match` header with entity tags is used in conditional GET requests to optimize network traffic by reducing unnecessary data transfers. By including this header, the NF Service Consumer asks the NRF to return the requested resource only if its current version differs from the one identified by the provided entity tag(s), i.e., if it has been modified since the last retrieval.