A unit rate is a ratio that compares a quantity to one unit of another quantity. Among the options you provided, the fraction that qualifies as a unit rate is:
Start Fraction 27 over 1 End Fraction (or 27)
This fraction represents a rate of 27 units of one quantity to 1 unit of another, which fits the definition of a unit rate.
The other options either represent whole numbers or fractions that do not indicate a comparison to one unit.