This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Umblicial cord and diaphragm, Subject name: Anatomy
Physiological umbilical hernia reduces because:- 
Select and explain. 
A. Regression of mesonephric kidney, B. Reduced growth of liver, C. Expansion of abdominal cavity, D. All of above
D: All of above
Answer: D: All of above 
Explanation: During the 6th week, the primary intestinal loop grows rapidly, as a result of rapid growth and expansion of liver, the abdominal cavity temporarily becomes too small to contain the loops of intestine and they enter to the extra embryonic coelom forming the physiological umbilical hernia. During the 10th week of development, the herniated intestinal loops sta to return to abdominal cavity. Although the factors responsible for it are not known, it is thought that regression of mesonephric kidneys, reduced growth of liver and expansion of abdominal cavity play impoant role.