Task: Question Answering
Input (English): Problem: at a contest with 2000 participants , 1 / 2 of the people are aged 16 to 18 . next year , the number of people aged 16 to 18 will increase by 1 / 4 . after this change , what percentage of the total 2000 people will the 16 - to 18 - year - olds represent ? 
Options: a ) 62.50 % , b ) 60 % , c ) 70 % , d ) 65 % , e ) 66 / 3 %
Output (English): a