The question is badly worded - the answer is indeterminate unless you know how many ports there are on the switch.
The answer is probably 100 megabits, as even basic routers have 4 LAN ports on them, so connecting 2 devices into those ports directly will allow 100 megabit connectivity between them.
The answer they are probably looking for is 10 megabits, which assumes that only 2 ports on the router are in use, and all the devices are plugged into the 10 megabit switch. This is a really dumb way of wiring things up.
I guess the point is to test that the student knows the slowest device in the path defines the maximum throughput.