A 42-Year-Old Woman Visited Her Physician Because She Experienced an Agonizing

A 42-year-old woman visited her physician because she experienced an agonizing pain in the rectum, which occurred on defecation. She had first noticed the pain a week before when she tried to defecate. The pain lasted for about an hour, then passed off, only to return with the next bowel movement. She said that she suffered from constipation and admitted that sometimes her stools were streaked with blood. After a careful examination, a diagnosis of anal fissure was made.
-The following statements concerning this case are correct except which?

A) Examination of the anal canal was difficult because any attempt to insert a gloved finger into the canal caused severe pain.
B) The anus was kept tightly closed by the spasm of the external anal sphincter.
C) Gentle eversion of the anal margin under local anesthesia revealed the lower edge of a linear tear in the posterior wall of the anal canal; a small tag of skin projected from the lower end of the tear.
D) The forward edge of a hard fecal mass may have caught one of the anal valves and torn it downward as it descended.
E) Anal fissures tend to occur on the anterior and posterior walls of the anal canal because the mucous membrane is poorly supported in this region by the superficial external sphincter muscle.
F) The mucous membrane of the lower half of the anal canal is innervated by autonomic afferent nerves and is sensitive only to stretch.