Final answer:
The value for age with the second-highest frequency in a data set is the mode. The correct answer is option a).
Step-by-step explanation:
The value for age with the second-highest frequency in a data set is referred to as the mode. The mode is the value or values that appear most frequently in a data set. When there are two values that have the highest frequency, the data set is called bimodal.
On the other hand, the value with the lowest frequency does not have a specific statistical term and is simply the least common value or values. In the context of descriptive statistics, the mean and median are also measures of central tendency but do not specifically relate to frequencies of individual values.
The mean is the average of all values in the data set. The median is the middle value when the data set is ordered. Finally, the range is the difference between the highest and lowest values in the data set.