We have no idea how many there are, and we already know about one, right? It seems like the simplest possibility.
Zero, if it was a single MP then you’d have already seen action to remove them.
How? I’m pretty sure the commentators have said there’s no mechanism to do that, exactly in Han Dong’s case.
This might make sense if you can’t count higher than one.
There is a room with a large-ish group of people in it. Someone in it has won a lottery. How many people in the room have winning lottery tickets, if you had to estimate?
An MP being a spy is more likely than winning a lottery, but I still think it’s fair to say the vast majority aren’t. To the point where if it’s not zero one seems most likely.
Edit: Even if my conclusion turns out to be wrong, I stand by this logic. Vote me down all you want.