Task: Question Answering
Input (English): Problem: pipe a usually fills a tank in 2 hours . on account of a leak at the bottom of the tank , it takes pipe a 30 more minutes to fill the tank . how long will the leak take to empty a full tank if pipe a is shut ? 
Options: a ) 7 hours , b ) 8 hours , c ) 9 hours , d ) 10 hours , e ) 11 hours
Output (English): d