:5. A box contains six tickets, 3 black and 3 white.  Two of
the black tickets are marked with a 2, and the other black ticket
is marked with a 3.  One of the white tickets is marked with a 2,
and a second one with a 3.  The third white ticket is as yet
unmarked.  A single draw is to be made at random from the box. 
What number should be written on the unmarked white ticket in
order that the color of the ticket drawn be independent of the
number on it? <p>

a.  color and number are independent no matter what number  
     is put on the remaining white ticket  <p>

b.  1 <p>

c.  2  <p>

d.  3 <p>

e.  color and number are never independent <p>