**Core Concept**
Measures of dispersion are statistical tools used to quantify the variability or spread of a dataset around its central value. In this context, the central value could be the mean, median, or mode. Measures of dispersion help in understanding the distribution of data and are essential in hypothesis testing, regression analysis, and research studies.

**Why the Correct Answer is Right**
Variance is a measure of dispersion that calculates the average of the squared differences from the mean. It is expressed in square units of the original measurement and is sensitive to extreme values in the dataset. Variance is an important measure of dispersion, but it is not a measure of central tendency. In contrast to variance, standard deviation is the square root of variance and is expressed in the same units as the original measurement.

**Why Each Wrong Option is Incorrect**
**Option A:** Mode is a measure of central tendency, not dispersion. It is the most frequently occurring value in a dataset and does not account for the spread of data.
**Option C:** Standard deviation is a measure of dispersion that calculates the average distance from the mean. It is expressed in the same units as the original measurement and is a key indicator of data spread.
**Option D:** Mean is a measure of central tendency, not dispersion. It is the average value of a dataset and does not account for the spread of data.

**Clinical Pearl / High-Yield Fact**
When analyzing data, it's essential to distinguish between measures of central tendency (mean, median, mode) and measures of dispersion (variance, standard deviation). Understanding the type of data and the research question can help you choose the appropriate measure of dispersion.

**✓ Correct Answer: B. Variance**