Four letter-clusters have been given, out of which three are alike in some manner and one is different. Select the letter-cluster that is different.
Note: The odd one out is not based on the number of consonants/vowels or their position in the letter cluster.

Logic: For the given letter clusters, add consecutive natural numbers in decreasing order (3, 2, and 1) to the corresponding letters of the clusters to find the next respective letters in each cluster.

(a) BEHI → B + 3 = E; E + 3 = H; H + 1 = I

(b) TWYZ → T + 3 = W; W + 2 = Y; Y + 1 = Z

(c) PSUV → P + 3 = S; S + 2 = U; U + 1 = V

(d) FIKL → F + 3 = I; I + 2 = K; K + 1 = L

From the analysis, we can see in options, (b), (c), and (d), that the letters in the letters cluster follow the same pattern. In option (a), the letters in the letter cluster do not follow the same pattern.

Therefore, the odd one out of the given options is BEHI.

Thus, the correct option is (a).