The correct answer is option B: There are between 15 and 20 green pieces in all 5 packages
The most important factor has been given which is, "Which statement about the candy pieces in the remaining packages is best supported by this information."
The information given is such that, the first package she opened had 4 green pieces and on this basis we can safely assume that all other packages have 4 green pieces as well. The second package had 3 green pieces and this based on this too we can safely assume that all other packages had 3 green pieces. Hence, all 5 packages can either have a total of 4 x 5 green candies which equals a total of 20 green pieces or, all 5 packages can have a total of 3 x 5 green candies which equals a total of 15 green pieces.
So according to Suzi's experiment, there are between 15 and 20 green pieces in all 5 packages.