The rectouterine pouch is the correct answer. This pouch along with the vesico-uterine pouch are made by the peritoneum draping over the pelvic organs. They are the lowest reaching extents of the peritoneal cavity. The uterus folds over the bladder allowing the rectouterine pouch to extend lower than the vesico-uterine pouch. It should be noted that the rectovesicular pouch is definitely incorrect at this can only be found in males.
However, if it were found in females, this would in fact, be the correct answer. Also, the paravesicular fossa is near the bladder allowing it to expand but it does not extend very low.
1. rectouterine pouch-The rectouterine and vesicouterine pouches are the two pouches created by draping the peritoneum over the pelvic organs. these pouches are the two lowest extents of the peritoneal cavity, so to answer this question, you just need to decide which one goes lower. since the uterus is folded over the bladder, the rectouterine pouch can extend to a slightly lower level than the vesicouterine pouch, which makes c the correct answer. the pararectal fossa is formed by lateral reflections of perineum over the superior one-third of the rectum; this space gives the rectum room to fill with feces. the paravesicular fossa is a space near the bladder that allows the bladder to expand. why is the rectovesicular pouch incorrect? it's only found in males, not females! (but, if the question had asked about males, the rectovesicular pouch would have been the correct answer.)