BIMN : CKPR : : CURD : ?

In given sets of alphabets, in first two sets BIMN and CKPR, difference of number of alphabet in alphabatical order is increasing 
As in 2nd set C comes just after B from first set of alphabets
Now in 2nd set K comes 1 ahead from I, in first set 
P comes 2 ahead from M, in first set
And R comes 3 ahead from N , in first set
Following this pattern missing set will be made through CURD and it will be DWUH.