Final answer:
The range of a relation is defined as the set of all possible output values, or y-values (Option B). It is distinct from the domain, which is the set of all possible input values.
Step-by-step explanation:
The best definition of the range of a relation is: B. The set of all possible output values, or y-values. To understand this concept, it is essential to identify the difference between 'domain' and 'range' in relations and functions. In mathematics, the domain refers to all the possible input values (typically represented by x-values), while the range refers to all of the possible output values derived from those inputs (typically represented by y-values).
For example, if we have a function that squares its input x, the resulting outputs (y-values) are the squares of the inputs. The domain could be all real numbers, as we can square any real number, but the range would be all non-negative real numbers because a square of a real number cannot be negative.