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
Criteria for diagnosis of gestational trophoblastic neoplasia includes all except 
Select and explain. 
A. Plateau of serum β-hcG levels for 4 measurements during a period of 3 weeks, B. Rise in serum β-hcG levels > 10% during 3 weekly consecutive measurement, C. Serum β-hcG levels remain detectable for 3 months only, D. Histological evidence of choriocarcinoma
C: Serum β-hcG levels remain detectable for 3 months only
Answer: C: Serum β-hcG levels remain detectable for 3 months only 
Explanation: TABLE 20-3. Criteria for Diagnosis of Gestational Trophoblastic Neoplasia

Plateau of serum β-hcG level (+ 10 percent) for four measurements during a period 3 weeks or longer - days 1, 7, 14, 21.
Rise of serum β-hcG level > 10 percent during three weekly consecutive measurements or longer during a period of 2 weeks or more - days 1, 7, 14.
Serum β-hcG level remains detectable for 6 months or more
Histological criteria for choriocarcinoma.