Please help me figure this out

Answer:
B. The rate of change of the cost of parking is $8.00 per hour.
Step-by-step explanation:
The cost for parking at the airport is modeled by the function;
[tex]c(x)=8x+10.00[/tex]
This means that, there is a fixed cost of $10.00 and additional cost of
$8.00 every hour.
The slope refers to the unit rate which is $8.00
The correct answer is B.