Task: Question Answering
Input (English): Problem: the difference between the heights of two trees is 20 cm . 10 years ago , the taller one was thrice as taller as the shorter one . the present height of the taller tree is 
Options: a ) 300 cm , b ) 15 cm , c ) 20 cm , d ) 10 cm , e ) 40 cm
Output (English): a