Task: Question Answering
Input (English): Problem: bag contains 7 green and 8 white balls . if two balls are drawn simultaneously , the probability that both are of the same colour is - . 
Options: a ) 7 / 15 , b ) 2 / 8 , c ) 7 / 11 , d ) 13 / 5 , e ) 87
Output (English): a