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: Medicine
Which of the following is the Post - Chemotherapy based staging system in Wilm's tumor: 
Select and explain. 
A. National Wilm's Tumor staging System (NWTSG), B. National Wilm's Tumor staging System (NWTSG), C. AJCC TNM, D. Chadwick
B: National Wilm's Tumor staging System (NWTSG)
Answer: B: National Wilm's Tumor staging System (NWTSG) 
Explanation: Answer is B (International Society of Pediatric Oncology-STOP) : The post-chemotherapy based staging system is the `SLOP' staging system developed by the International society of pediatric oncology.