The unit rate is the speed of the car in miles per hour. Since the car travels 110 miles in 2 hours, you can calculate the unit rate as follows:
\[ \text{Unit Rate} = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{110 \text{ miles}}{2 \text{ hours}} = 55 \text{ miles per hour} \]
So, the correct response is:
55 miles per hour