The rationale behind Order XXII Rule 9 explains why sufficient cause is the deciding factor here. The rule exists so that a suit does not collapse merely because a party's heirs were not brought on record in time, provided the delay was genuine and not the result of negligence.
Only sufficient cause for the delay fits the statutory test.
The correct answer is sufficient cause for not making the application within time.
Abatement under Order XXII of the CPC is a procedural consequence, not a permanent bar, and the Code deliberately builds in a mechanism to undo it when the failure to act in time was excusable. Looking at what each option would mean if it were the real test helps confirm which one the law actually uses.
Only the sufficient cause standard keeps the limitation safeguard workable while still allowing genuine hardship cases to be revived, which is why it is the test applied under Order XXII Rule 9.
The correct answer is sufficient cause for not making the application within time.