E.

Come on now. You didn't expect the whole alphabet to be in that generic alphabet style, did you? You had to know that at least one letter would be in Gritty Sharpness or else we'd all have to cry. And E. seemed the best letter in the near future to fill the role, though X or Z would also have worked well in the position

Also in response to the earlier comment. Everyone knows that A, B and C are supposed to be Green , Red and Blue, respectively. At least that's how it is in the North East. Though regardless... Mine is wrong.