**Core Concept**
The question is inquiring about the best measure of central tendency, which is a statistical concept used to describe a set of data by providing a single value that best represents the entire dataset. The three primary measures of central tendency are mean, median, and mode.

**Why the Correct Answer is Right**
The mean is the average value of a dataset, calculated by summing all the values and dividing by the number of values. It is the most commonly used measure of central tendency and is particularly useful when the data is normally distributed. However, the mean can be skewed by outliers, which makes it less reliable in certain situations. In contrast, the median is the middle value of a dataset when it is ordered from smallest to largest, and it is a better representation of the central tendency when the data is skewed or has outliers. The mode is the value that appears most frequently in a dataset, but it is not always unique and can be problematic when there are multiple modes.

**Why Each Wrong Option is Incorrect**
**Option A:** The median is a measure of central tendency, but it is not the best measure in all situations, especially when the data is normally distributed.
**Option B:** The mode is a measure of central tendency, but it can be problematic when there are multiple modes or when the data is not normally distributed.
**Option C:** The range is a measure of dispersion, not central tendency.

**Clinical Pearl / High-Yield Fact**
In statistics, the choice of measure of central tendency depends on the distribution of the data and the presence of outliers. When in doubt, start by calculating the mean and then consider the median or mode if the data is skewed or has outliers.

**Correct Answer:** D. The mode.