Choose the missing item in the series:
CDFG, IJLM, OPRS,_____, ABDE

Considering the first letter of given terms 
it forms pattern
C , I ,O,_ ,A
I and C have 5 alphabets between them , I and O also have 5 alphabets between them so we get first term as U .
Now considering 2nd letter of given terms :
D,J,P _,B
Here again D and J have 5 alphabets between them
J and P have 5 alphabets between them
So next letter will be V
so we get UV
We can conclude the answer will be UVXY