Answer:
C. 
Step-by-step explanation:
Let x represent number of miles.
We have been given that a taxi cab charges $1.50 for the flat fee and $0.50 for each mile.
The cost of riding x miles would be
and the total cost of riding x miles would be
.
Since Sharon has only $25 to spend on the taxi ride, so the cost of riding x miles on taxi must be less than or equal to 25.
We can represent this information in an inequality as:

Therefore, option C is the correct choice.