Under Order XXII of the CPC, a suit abates if legal representatives of a deceased party are not brought on record in time, and the question asks what the plaintiff must show to have that abatement set aside. Each option needs to be checked against the actual ground recognised for setting aside abatement.
Only a showing of sufficient cause for the delay matches what Order XXII Rule 9 actually requires of the plaintiff.
Therefore, the correct answer is Sufficient cause for not making the application within time.