C L R T B Q S M A P D I N F J K G Y X Four of the following five are alike in a certain way and so form group. Which is the one that does not belong to the group? 1. LBT 2.IJF 3. PID 4. BMS

$L\to +3B\to -1T$

  $I\to +3J\to -1F$

  $P\to +2I\to -1D$

  $B\to +3\to -1S$

  Therefore, PID is not in the form of other patterns.