the behavior of the game host as he will never reveal the door with the car this is the key bit. If the door you picked is the correct one (1% chance) the host

the behavior of the game host as he will never reveal the door with the car this is the key bit. If the door you picked is the correct one (1% chance) the host can open any door. If you picked incorrectly (99% chance) he can open any door except the winning door so the remaining door will be the correct one 99% of the time.