|A) 2 : 5||B) 8 : 15|
|C) 9 : 10||D) 3 : 5|
The ratio of X and Y ages at present is 4:5.
Then, the ratio 20 years ago will not be more than the ratio at present.
So, from the options 9:10 is not satifying => its ratio is 0.9 which is greater than presnt ratio of 0.8.