Three of the following words are alike in some manner and hence form a group. Which word does NOT belong to that group? (The words must be considered as meaningful English words and must not be grouped base d on the number of letters/vowels/consonants).

Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus form a group. Which letter-cluster pair DOES NOT belong to that group? (Note: The odd one out is not based on the number of consonants/vowels or their position in the letter-cluster.)

Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus form a group. Which letter-cluster pair DOES NOT belong to that group? (Note: Positions of letters from the beginning and end are paired as opposites, e.g., Y-B, G-T, H-S, R-I; sum of positions = 27)