In MikroTik's Simple Queues, the target-address field is used to define the IP address of the device (host) to which the queue will apply. This must be an IP address - not a MAC address or an address list name.
Let's evaluate:
* A.#MAC address is not supported as target-address in simple queues
* B.#"server's address" is vague; if it means an IP, then it could work, but the best answer is "client's address"
* C.#Address lists can be used in firewall and mangle rules, but not directly in simple queues
* D.#Correct - An individual IP address (like 192.168.1.100) can be assigned as the target-address MTCNA Course Manual - Simple Queue Structure:
"Use the target-address field to apply a queue to a specific host by IP." Rene Meneses Guide - Queue Setup:
"Only IP addresses can be used as targets in simple queues. Address lists are not accepted." Terry Combs Notes - Bandwidth Limiting:
"Target-address = device IP. MACs and lists are not allowed here."