Task: Question Answering
Input (English): Problem: in a class of 40 students , 5 students did not borrow any books from the library , 15 students each borrowed 1 book , 10 students each borrowed 2 books , and the rest of the students each borrowed at least 3 books . if the average ( arithmetic mean ) number of books borrowed per student was 2 , what is the maximum number of books that any single student could have borrowed ? 
Options: a ) 3 , b ) 5 , c ) 8 , d ) 13 , e ) 18
Output (English): e