It might be stated that his reliability might be compromised because he writes the story many years later and his memories may be skewed. he is the narrator and the protagonist of the story and it is written in first person so he retells what he remembers from his life experience since he was a child.
A is the answer. It’s like addition.
The defecation reflex involves two postive feedback loops. these loops are the stretch receptors in the rectal walls and the sacral parasympathetic system. Defecation reflex empties the rectum by peristaltic movements push fecal matter from the sigmoid colon into the rectum. Then this distension of the rectal walls stimulates stretch receptors which results in defecation.