What should come in place of '?' in the given series based on the English alphabetical order?

TKF, UJG, VIH, WHI, ?

Given: TKF, UJG, VIH, WHI, ?

Logic: First letters +1, second letters -1, third letters +1 in English alphabet.

1st Letters:
T + 1 = U; U + 1 = V; V + 1 = W; W + 1 = X 
2nd Letters:
K - 1 = J; J - 1 = I; I - 1 = H; H - 1 = G
3rd Letters:
F + 1 = G; G + 1 = H; H + 1 = I; I + 1 = J 
The next term in the series is XGJ.
Thus, the correct option is (a) XGJ.​​​​