Final answer:
Routers are designed not to forward IPv4 broadcast packets by default, while an Ethernet switch will forward broadcasts within the same local network, and a Windows PC will process the broadcasts within the same subnet.
Step-by-step explanation:
The devices that will not forward an IPv4 broadcast packet by default are routers. An Ethernet switch (A) will forward broadcasts within the same broadcast domain, typically a local network. A Windows PC (C) will receive and process the broadcast if it's within the same subnet. However, routers (B) are designed to not forward broadcast packets; they limit broadcast traffic to within a single network (broadcast domain), and do not propagate it to other networks.