Task: Question Answering
Input (English): Problem: in a certain game , a large bag is filled with blue , green , purple and red chips worth 1 , 5 , x and 11 points each , respectively . the purple chips are worth more than the green chips , but less than the red chips . a certain number of chips are then selected from the bag . if the product of the point values of the selected chips is 28160 , how many purple chips were selected ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5
Output (English): c