This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
[{'content': 'Pain in endometrium is closely associated with \nSelect and explain. \nA. site of endometrium, B. depth of invasion, C. stage of disease, D. size of lesion', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans B Ref: Williams gynaec page 230Underlying cause of pain is unclear: proinflammatory cytokines (PGF2alpha) released by the endometriotic implants into peritoneal fluidEvidence to suggest that pain from endometrium correlate to depth of invasion and site of pain- many indicate lesion location.Recent data suggest pain result from neuronal invasionRef: Sheila Balakrishnan, gynaec page 143Severe endometriosis can produce pain by peritoneal inflammation, deep infiltration and scarring, invasion of nerve endings, adhesions, collection of menstrual blood.', 'role': 'assistant'}]