Hello Ricardo!
The ip directed-broadcast command is issued on the outgoing interface of a router that connects to the subnet that you want the direct broadcasts to be forwarded to. If you have multiple routers between the source of the directed broadcast and the intended destination, then you would simply apply the command to all of the intervening routers, on the outgoing interfaces that reach the network in question. Just keep in mind that these directed broadcasts will be sent on all intervening subnets as well, which could cause network inefficiencies, so it should be done with caution.
WoL requires that the IP directed-broadcast feature be supported on the last router to the destination subnet. If we want to enable WoL for the workstations, then the answer is D. If we want WoL to be enabled on the application server, then A is the answer.
I hope this has been helpful!
Laz