The correct answer is A. Range.
The range is the simplest measure of dispersion. It is the difference between the largest and smallest values in a set of data. The range is easy to calculate and interpret, but it is not very sensitive to changes in the data.
The quartile deviation is the median of the absolute deviations from the median. It is also known as the semi-interquartile range. The quartile deviation is more resistant to outliers than the range, but it is still not very sensitive to changes in the data.
The mean deviation is the average of the absolute deviations from the mean. It is also known as the average absolute deviation. The mean deviation is more sensitive to changes in the data than the range or the quartile deviation, but it is still not very resistant to outliers.
The standard deviation is the square root of the variance. It is the most common measure of dispersion. The standard deviation is more sensitive to changes in the data than the range, the quartile deviation, or the mean deviation, and it is also more resistant to outliers.
However, the standard deviation is not appropriate for open-ended sections. This is because the standard deviation is calculated using the squared deviations from the mean. In an open-ended section, there is no upper limit to the values, so the squared deviations from the mean can be very large. This can make the standard deviation difficult to interpret.
Therefore, the range is the most appropriate measure of dispersion for open-ended sections.