48 year old male reported with the chief complaint of ulcer on the gums and on general examination headache, fever and malaise was observed. On oral examination, sharply punched out crater-like erosions of the interdental papillae of sudden onset were noted. The patient also complained of bad breath.

This patient's lower anterior marginal gingiva showed comma-shaped defect called
Stillman's cleft
Dehiscence
Fenestration
Cul-de-sac