Task: Question Answering
Input (English): Problem: find the compound ratio of ( 1 : 2 ) , ( 2 : 3 ) and ( 3 : 4 ) is 
Options: a ) 1 : 2 , b ) 3 : 5 , c ) 5 : 7 , d ) 1 : 4 , e ) 2 : 1
Output (English): d