1970 Draft Lottery

And also I have a trouble with this:

Based on the box plots, which statement is correct?
a) There seems to be no relationship between birth month and draft lottery.
b)There is a weak negative correlation between birth day and draft lottery number.
C) Since the spread for each month is about the same, the mean draft lottery number for each month is about the same.
d)Those people born near the end of the year tended to be assigned lower draft lottery numbers than those born at the first of the year.
e) Since there is a region common to all box plots the confidence intervals for each month all cover the similar value for the mean draft lottery number.

From my point of view D) is the best answer. Is it? And also what are "the confidence intervals"?

Thank you...