Question

PLEAS HELP.

Answer 1

A: put an atom on a poster in the exhibit
     Good luck.  The poster itself is made of trillions of trillions of trillions
     of atoms.  You could not see the extra one any easier than you could
     see the ones that are already there, and even if you could, it would be
     lost in the crowd.
 
B: use a life size drawing of an atom
     Good luck.  Nobody has ever seen an atom.  Atoms are too small
     to see.  That's a big part of the reason that nobody knew they exist
     until less than 200 years ago.

D: set up a microscope so that visitors can view atoms
     Good luck.  Atoms are way too small to see with a microscope.

C: Display a large three dimensional model of an atom.
     Finally !  A suggestion that makes sense.
     If something is too big or too small to see, show a model of it
         that's just the right size to see.