Task: Question Answering
Input (English): Problem: each of 3 charities in novel grove estates has 8 persons serving on its board of directors . if exactly 4 persons serve on 3 boards each and each pair of charities has 5 persons in common on their boards of directors , then how many distinct persons serve on one or more boards of directors ? a . b . c . d . e . 
Options: a ) 8 , b ) 13 , c ) 16 , d ) 24 , e ) 27
Output (English): b