Concept:The mode is the value that appears most frequently in a set of data.
Explanation:The mode is defined as the observation with the highest frequency.
First, list the observations and count how many times each value occurs.
The value that occurs the greatest number of times is the mode.
Option A says “observation with the highest frequency,” which exactly matches this definition.
Option B describes the median for an even number of items, as the average of the two middle numbers.
Option C also describes the median, as the item that occupies the middle position in an ordered set.
Option D describes the range, which is the difference between the largest and smallest values.
Therefore, the best description of the mode is the observation that occurs most often.
Answer:A. observation with the highest frequency