Three of the four words are alike in a certain way and one is different. Pick the odd one out. 

Solution

The logic followed here is: The second letter of the word is fourth preceding letter of the first letter, third letter of the word is third preceding letter of the second letter and fourth letter of the word is second preceding letter as per English alphabetical series. In option 'a': 'QMKH' → Q - 4 = M, M - 3 = J ≠ J, J - 2 = H In option 'b': 'ZVSQ' → Z - 4 = V, V - 3 = S, S - 2 = Q In option 'c': 'HDAY' → H - 4 = D, D - 3 = A, A - 2 = Y In option 'd': 'KGDB' → K - 4 = G, G - 3 = D, D - 2 = B