This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Most common causeof acute intestinal obstruction is : 
Select and explain. 
A. Small bowel adhesions, B. Intussusception, C. Tuberculosis, D. Malignancy
A: Small bowel adhesions
Answer: A: Small bowel adhesions 
Explanation: Intra-abdominal adhesions related to prior abdominal surgery account for upto 75% of the cases of small bowel obstruction. Intestinal Obstruction
Causes
Intraluminal (Eg. Foreign bodies, gallstones, or meconium)
Intramural (Eg. Tumors, Crohn’s disease – associated inflammatory strictures)
Extrinsic (Eg. Adhesions, hernias, or carcinomatosis)
Clinical Presentation :
Colicky abdominal pain, nausea, vomiting, abdominal distension and constipation are seen.
Constipation is not seen in : Richter’s hernia obstruction, gall stone obstruction, mesenteric vascular occlusion.
Vomiting is a more prominent symptom with proximal obstructions than distal.