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: Surgery
In choriocarcinoma, lung metastasis occurs in which stage? 
Select and explain. 
A. Stage 1, B. Stage 2, C. Stage 3, D. Stage 4
C: Stage 3
Answer: C: Stage 3 
Explanation: Answer- C. Stage 3FIGO Classification* Stage I Disease confined to uterus.* Stage II Extends outside of the uterus but is limited to the genital structure ( adnexa, vagina, broad ligament.)* Stage III Extends of the lungs , with or without known genital tract involvement.* Stage IV meatastases to other organs ( Brain, liver, Kidney, Ovaries, Bowel).