To find the unit rate (speed) from a distance vs. time graph, you need to determine the change in distance over the change in time.
From the point you provided (5, 255), we assume it means that after 5 hours, Oey traveled a distance of 255 miles.
To calculate the speed:
- Distance traveled: 255 miles
- Time taken: 5 hours
Now, divide the distance by the time to find the speed (unit rate):
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{255 \text{ miles}}{5 \text{ hours}} = 51 \text{ miles per hour} \]
Based on this calculation, since 51 miles per hour is not one of the options provided, we may be slightly off and should check what values are typically used in the options.
Given the closest option to 51 miles per hour would most likely round down to:
B. 50 miles per hour
If the graph suggests a slightly different time or distance, please provide that information for a more accurate result. However, based on the current details, the correct answer from the choices given is B. 50 miles per hour.