When drawing a histogram, it's important to:

a) make sure the bottom edge of each bar is placed along the corresponding class interval.
b) make sure the mean and median are contained in the same class interval so that the correct type of skewness can be identified.
c) make sure the heights of the bars exceed the widths of the class intervals so that the bars are true rectangles.
d) have a seperate class interval for each observation to get the most informative plot.
e) none of the above.