For recovery, we'll be having 2 choices, either Deferred updation or Immediate updation techniquee.
Now If we take Deferred Updation which says only REDO and no UNDO then no option is matching.Then we'll take Immediate Updation, which is having two choices further as UNDO/No-REDO and UNDO/REDO.
If we follow UNDO/No-REDO then we'll have to UNDO active transaction T2 only (no REDO on T1 as changes are immediate to DB and T1 already committed).Again no option matches with this choice.
So we'll follow UNDO/REDO which says that all committed transactions up to checkpoint need not be REDO, committed but not checkpointed are need to be REDO and active transaction need to be UNDO.Hence T2 needs UNDO and then T1 needs REDO. Thus, answer is option B