At an amusement park, you and your friends have the opportunity to enter a room while others look in and observe. What they observe is rather odd

Among your friends are twins who enter the room and seem to be radically different in height despite the fact that they are identical twins. You recognize that this exhibition is based on the
a) Ames room.
b) Muller-Lyer illusion.
c) Barnum effect.
d) Ebbinghaus illusion.

ANS: a