Hrm, tough choice. All three are decent options, and could lead to something good.
I... guess B? I don't mind Twisted Treeline, and it's interesting to see how you change/ explain the Mejai's. I know there is going to be a fight eventually, but might as well give the three a chance to acclimate when they go through.
And of course, I'm thrilled you're including Irelia. She was my first champ outside of training and I always enjoy playing her, so seeing her in action is great. I'm interested to see how long her and Kat work together smoothly, though...
"Ironically, the word mature when applied to games tends to have a very childish connotation." -Erik J. Caponi of Bethesda Softworks