Why must class intervals of a grouped frequency distribution be converted to continuous form before drawing its histogram?
(a) It converts discrete data into continuous form, which a histogram needs.
(b) It forces all classes to have equal widths, which is compulsory for a histogram.
(c) It removes gaps between adjacent rectangles, so that the area of each rectangle truly represents its frequency.
(d) It makes the class marks whole numbers, allowing the bars to be located exactly on the x-axis.