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: Gynaecology & Obstetrics
Which of the following is a risk factor for the develoment of Choriocarcinoma? 
Select and explain. 
A. Presence of Lung metastasis, B. Onset following term gestation, C. b-hCG level < 40,000 mlU/mL, D. None of the above
B: Onset following term gestation
Answer: B: Onset following term gestation 
Explanation: Poor-prognosis patients, based on the Clinical Classification of Malignant Disease, are those with any of the following risk factors: *Serum b-hCG titers greater than 40,000 mlU/mL at the onset of treatment *Diagnosis of disease more than 4 months after molar pregnancy *Brain or liver metastases *Prior unsuccessful chemotherapy *Onset following term gestation.