C is the correct answer

A 3a perineal laceration is defined by < 50% of the external anal sphincter torn, 3b is when > 50% of the external anal sphincter is torn, and 3c laceration is when the entire external anal sphincter and internal anal sphincter are torn, not including the anal mucosa. The biggest risk factor is forceps delivery. Other risk factors include a midline episiotomy, vacuum-assisted delivery, increased fetal weight, primiparity, labor induction or augmentation, epidural anesthesia, persistent occiput-posterior position, and familial history. During repair of a third-degree laceration, the internal anal sphincter, a glistening white fibrous structure between the mucosa and the external anal sphincter, is sutured in a continuous, nonlocking fashion.

The anal mucosa (A) is sutured during fourth-degree lacerations, paying attention not to enter the rectal lumen. The external anal sphincter (B) is a dark red muscle that retracts laterally. It can be grasped with Allis clamps and sutured together by the end-to-end or overlapping fashion. The transverse perineal muscle (D) is repaired in second- to fourth-degree lacerations and is a dark red muscle.