Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.

MANZ, OAPZ, QARZ, ?

​Logic: 1st and 3rd letters are increasing by +2, 2nd and 4th letters no change.

First letters: M + 2 = O, O + 2 = Q, Q + 2 = S.

Second letters: No change (A) 

Third letters: N + 2 = P, P + 2 = R, R + 2 = T

Fourth letters: No change (Z) 

Now, the next term will be SATZ.

Thus, the correct option is (d) SATZ.

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