Find the missing term in the following series:
AZ, GT, M, ?, YB
[A]JH
[B]SH
[C]SK
[D]TS

SH
In the above question, the pattern is,
1st letter
$latex A\xrightarrow{\text{+6}} G\xrightarrow{\text{+6}} M\xrightarrow{\text{+6}} \textcircled{S} \xrightarrow{\text{+6}} Y$
2nd letter
$latex Z\xrightarrow{\text{-6}} T\xrightarrow{\text{-6}} N\xrightarrow{\text{-6}} \textcircled{H} \xrightarrow{\text{-6}}B$