Here the main confusion that is created is between option B and D.
As we know SELECT statement can return duplicates , so is the case here.
Suppose u have 6 values 1,2,3,4,5,5 then the query mentioned in option B will return all the 6 tuples i.e. 5,5,4,3,2,1 whereas if you use query mentioned in option D , it will return 5,4,3,2,1.
Plz consult this link :(This may help you further and remove any further doubt if you have)
http://stackoverflow.com/questions/20853725/what-is-the-use-of-with-ties-keyword-in-select-statement-in-sql-queries
Hence the correct option to the above question would be option D.