Task: Question Answering
Input (English): Problem: in a certain pond , 40 fish were caught , tagged , and returned to the pond . a few days later , 40 fish were caught again , of which 2 were found to have been tagged . if the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond , what ` s the approximate number of fish in the pond ? 
Options: a ) 400 , b ) 800 , c ) 1250 , d ) 2500 , e ) 10 000
Output (English): b