ZKU
In the above question, the pattern is ,
1st letter
$latex A\xrightarrow{\text{+3}}D\xrightarrow{\text{+4}}H\xrightarrow{\text{+5}} M\xrightarrow{\text{+6}} S\xrightarrow{\text{+7}} \textcircled{Z} $
2nd letter
$latex B\xrightarrow{\text{+5}}G\xrightarrow{\text{+6}}M\xrightarrow{\text{+7}} T\xrightarrow{\text{+8}} B\xrightarrow{\text{+9}} \textcircled{K} $
3rd letter
$latex D\xrightarrow{\text{+7}}K\xrightarrow{\text{+8}}S\xrightarrow{\text{+9}} B\xrightarrow{\text{+10}} L\xrightarrow{\text{+11}} \textcircled{W} $