Select the option that does NOT belong to the given series:

EC, H, HF, N, KI, U

U

 Alphabet :          E C    H       H F       N       K I      U

Numerical Value: 5,3     8       8,6      14      11,9    21

In this question the sum of numerical values gives the next alphabet, like,

EC : 5 + 3 = 8 which is the numerical value of H

HF : 8 + 6 = 14, which is the numerical value of N

And hence,

KI : 11 + 9 = 20, which is the numerical value of T

So, in this question U is the wrong answer.