In the context of domain expansion in mathematics, which of the following statements best describes the concept of expanding a function's domain?
A) Domain expansion involves increasing the range of a function to include additional values beyond the initial output set.
B) Domain expansion involves extending the set of input values for which a function is defined, potentially including values that were previously excluded.
C) Domain expansion focuses on decreasing the dimensionality of a function to simplify its analysis.
D) Domain expansion refers to reducing the number of variables in a function to make it easier to solve.