Answer : All of the above
Broadcast packets are not routed and forwarded by the routers on any network.
Broadcast routing can be done in two ways :
A router creates a data packet and then sends it to each host one by one. In this case, the router creates multiple copies of single data packet with different destination addresses. All packets are sent as unicast but because they are sent to all, it simulates as if router is broadcasting.
Secondly, when router receives a packet that is to be broadcasted, it simply floods those packets out of all interfaces. All routers are configured in the same way.This method is easy on router's CPU but may cause the problem of duplicate packets received from peer routers.
Reverse path forwarding is a technique, in which router knows in advance about its predecessor from where it should receive broadcast. This technique is used to detect and discard duplicates
Flooding is simplest method packet forwarding. When a packet is received, the routers send it to all the interfaces except the one on which it was received.