Final answer:
Option B, which is $1.45 per ounce, represents a unit rate because it expresses the cost for exactly one ounce.
Step-by-step explanation:
A unit rate is a comparison of two measurements where one of the quantities is one. Looking at the options provided, we need to identify which ratio is expressed with one unit of comparison. Specifically, we're looking for a measure per one unit of time, weight, or other standard measurements.
- A. 16 miles : 2 hours is not a unit rate because the time is not one hour.
- B. $1.45 : per ounce is a unit rate because the cost is given for exactly one ounce.
- C. 2 yards : 30 seconds is not a unit rate since the time is not one second.
- D. 20 inches : 4 hours is not a unit rate because the time is not one hour.
From the examples provided, the option that shows a unit rate is B, $1.45 per ounce.