Task: Question Answering
Input (English): Problem: the average weight of a group of boys is 30 kg . after a boy of weight 45 kg joins the group , the average weight of the group goes up by 1 kg . find the number of boys in the group originally ? 
Options: a ) 14 , b ) 15 , c ) 16 , d ) 17 , e ) 18
Output (English): a