(unknown artist)
@mc You switch because then you have a 50% chance of being right instead of 33%
@mc switch it to track c please. I hate people

@mc

You'd still choose A because that's where you're standing so you can jump on the trolley to hitch a ride.

@mc how does the man decide which curtain to reveal?
@mc Switch to track C, because then you can be sure 10 people can board the trolley. It would be inefficient if it could pick up only one passenger.
@mc This really depends on the strategy of the man that opened the door.