Task: Question Answering
Input (English): Problem: a runner runs the 40 miles from marathon to athens at a constant speed . halfway through the run she injures her foot , and continues to run at half her previous speed . if the second half takes her 4 hours longer than the first half , how many hours did it take the runner to run the second half ? 
Options: a ) 6 , b ) 7 , c ) 8 , d ) 9 , e ) 10
Output (English): c