Solution 
There are 2 pieces that 
are highlighted out of 4 pieces.  Thus, the probability that
a randomly chosen piece is highlighted is 1/2.
  Since odds is a ratio of the event happening
to the event not happening, we can simply take a ratio of the number
of pieces unhighlighted to the number of pieces highlighted.  In this case
that would be 2:2 which simplifies to 
1:1. 
 
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