Concept:In a histogram, the height of each rectangle directly indicates the frequency (number of data points) in that class interval.Explanation:A histogram uses adjacent bars to represent grouped numerical data. The width of each bar shows the class interval length, while the height shows how many observations fall within that interval. For example, if a class has 15 values, the rectangle’s height is proportional to 15. This height does not depend on the class limits or width; it purely reflects the frequency. Hence, looking at the height tells you which class has more or fewer occurrences.Answer:A. frequency of the class