What is the irony of the inscription hanging over the iron gate of Auschwitz?

Question

a
The sign welcomes the prisoners to Auschwitz when there is nothing welcoming about the camp.
b
The sign suggests that work makes them free, but they are not at all free; they work as slaves to the Nazis.
c
The sign is a decoy to make the Allies believe the camp is a hotel, but the conditions make it nothing like a hotel
d
The sign warns them against the dangers of escaping when nothing is more dangerous than what is happening inside the camp.

Answer 1

b
The sign suggests that work makes them free, but they are not at all free; they work as slaves to the Nazis.