The router connects to a switch which leaves 11 ports on the switch.
The hub also connects to a switch leaving 10 ports on the switch.
The 4 ports are open on the hub plus 10 ports on the switch makes it 14 collision domains.

One port on switch connects to router (1 collision domain). The other router port is not connected (0 collision domain). One port of the switch connects to the hub forming 1 collision domain. So with 10 ports left on the switch, I come up with 12 collision domain. You could possible consider the unused port of the router as one more. but my answer would be 12