An Ex-parte decree can be set aside under

Correct option is C

The correct answer is C. Under Order IX Rule 13 of the CPC, 1908, a defendant can apply to set aside an ex-parte decree if they provide sufficient cause for their absence. The court may grant the application if it finds the reason valid. Order IX Rule 7 deals with appearing before the decree, and Rule 9 concerns the plaintiff’s absence, so they are not applicable here.