Setting B causes conflict as the modem and router has the same ip. A common ip for modem is 10.0.0.1 and router is 192.168.1.1

There's no need to turn on DHCP if you've already fixed your IP on your network adapter as stated.

kytehx, you can use usb if your modem supports it. But you'll still need to install the drivers before plugging it into the usb port.