Review Question - QID 214628

A 67-year-old man presents to the clinic with a painful bulge on his abdomen. He first noticed the pain 2 years ago, and it has continued to get worse. Two months ago, he started noticing a bulge on his right lower abdomen when coughing and going to the bathroom. He denies nausea, vomiting, and changes in bowel movements. He has a history of constipation and melanoma on his left shoulder and right lower abdomen. Both lesions were removed with wide margin excisions. On exam, his abdomen is soft and nontender with normal bowel sounds. There is a 3-cm reducible defect located lateral to the rectus abdominis muscle and medial to a branch of the external iliac artery. There is a scar just superior to the defect that is clean and intact. Protrusion of intra-abdominal contents through which of the following is the most likely cause of this patient's symptoms?