Choose the odd one:

Let us look at the numerical positions of each letter in the standard alphabet to find the pattern:
* BdEg: $\text{B}(2)\stackrel{+2}{\to }\text{d}(4)\stackrel{+1}{\to }\text{E}(5)\stackrel{+2}{\to }\text{g}(7)$ — steps are $+2,+1,+2$.
* KmNp: $\text{K}(11)\stackrel{+2}{\to }\text{m}(13)\stackrel{+1}{\to }\text{N}(14)\stackrel{+2}{\to }\text{p}(16)$ — steps are $+2,+1,+2$.
* PrSu: $\text{P}(16)\stackrel{+2}{\to }\text{r}(18)\stackrel{+1}{\to }\text{S}(19)\stackrel{+2}{\to }\text{u}(21)$ — steps are $+2,+1,+2$.
* TwXz: $\text{T}(20)\stackrel{+3}{\to }\text{w}(23)\stackrel{+1}{\to }\text{X}(24)\stackrel{+2}{\to }\text{z}(26)$ — steps are **$+3$ **, $+1,+2$.

Because the first interval in TwXz is $+3$ instead of $+2$, it does not follow the same common rule and is the odd one out.