In the following question, a group of letters is given. The letters of each group are related with the letters of the same group by some Logic/Rule/Relation. From the given alternatives, select a group of letters which follows the same Logic/Rule/Relation.
(CN, YH, UB)
1
(DW, ZQ, VK)
2
(PF, LZ, FT)
3
(EX, AR, XL)
4
(LQ, HK, DF)