The right answers is B. Rational expression.
This is true given that the statement establishes a term that describes a fraction that has a variable or variable expression in its numerator, denominator or both, that is, this is the concept of the quotient of two polynomials called rational expression. Finally, we can get the following rational expressions that matches with this concept, namely:
\((1) \ \frac{1}{x} \\ \\ (2) \ \frac{2x-1}{x+1} \\ \\ (3) \ \frac{x^{2}-1}{x^{2}+1}\)
