Ans. is 'c' i.e., Neuroblastoma The commonest intra-abdominal tumor in first two years of life Neuroblastoma The commonest intra-abdominal tumor between 2"d to 5th year of life - Wihn's tumor The commonest intra-abdominal tumor in children (no age specification) Neuroblastoma (Wilm's tumor is the second most common abdominal tumor in children) Remember: The commonest cause of abdominal mass in Newborn is : Multiple dysplastic kidneys (if neoplasm or tumor has not been mentioned when asking for the commonest intra-abdominal mass, the answer will be multiple dysplastic kidneys)