Task: Question Answering
Input (English): Problem: the mall charges 50 cents for the first hour of parking and $ 3 for each additional hour until the customer reaches 4 hours , after that the parking fee is $ 1 per hour . if a certain customer parked his in the mall for 7 hours and 30 minutes , how much is he going to pay ? 
Options: a ) $ 11.5 . , b ) $ 12 . , c ) $ 13 . , d ) $ 14.5 , e ) $ 15 .
Output (English): c