Final answer:
A variable is a value that changes or varies over time, fitting best with option B. It can be numerical or categorical, quantitative or qualitative, and is pivotal for data representation and analysis in various fields.
Step-by-step explanation:
The correct definition of a variable is a data characteristic that stands for a value that changes or varies over time. This is represented by option B. Variables are essential in mathematics, statistics, and various scientific disciplines because they allow for the representation of data that can fluctuate. They come in different forms including numerical and categorical variables. Numerical variables are quantifiable and can be either discrete or continuous based on whether they result from counting or measuring. Categorical variables place items into different groups without any quantitative value associated with them.
For instance, if we denote X as a variable representing the number of points a student earns in a term, X is a numerical and possibly discrete variable, especially if these points can only take on integer values. On the other hand, if Y represents a person's political party affiliation, it is a categorical variable because it categorizes individuals into groups such as Republican, Democrat, or Independent. The variable X can be used to calculate the average score while using Y for such calculations would not be applicable.
In conclusion, variables are not constant; they vary and can be represented in equations and data sets, aiding in conducting analyses, forming predictions, and testing hypotheses. Therefore, the mentioned correct option in the final answer is B, a data characteristic that stands for a value that changes or varies over time.