Task: Question Answering
Input (English): Problem: a class consists of 15 biology students and 10 chemistry students . if you pick two students at the same time , what ' s the probability that one is maths and one is chemistry ? 
Options: a ) 2 / 7 , b ) 5 / 7 , c ) 1 / 2 , d ) 3 / 7 , e ) 1 / 2
Output (English): c