Which of the following terms will replace the question mark (?) in the given series?SOWJ, QPUK, OQSL, ?, KSON

Let's track the positional transitions for each letter in the cluster series:First Letter: S $\to$ Q $\to$ O $\to$ ? $\to$ KS(19) $-2=$ Q(17)Q(17) $-2=$ O(15)O(15) $-2=$ M(13)M(13) $-2=$ K(11)Second Letter: O $\to$ P $\to$ Q $\to$ ? $\to$ SO(15) $+1=$ P(16)P(16) $+1=$ Q(17)Q(17) $+1=$ R(18)R(18) $+1=$ S(19)Third Letter: W $\to$ U $\to$ S $\to$ ? $\to$ OW(23) $-2=$ U(21)U(21) $-2=$ S(19)S(19) $-2=$ Q(17)Q(17) $-2=$ O(15)Fourth Letter: J $\to$ K $\to$ L $\to$ ? $\to$ NJ(10) $+1=$ K(11)K(11) $+1=$ L(12)L(12) $+1=$ M(13)M(13) $+1=$ N(14)Combining these letters yields MRQM.