B

Rising or plateauing β-hCG levels and the appearance of metastases such as a vaginal/sub-urethral nodule are FIGO criteria for post-molar gestational trophoblastic neoplasia, and uterine enlargement after evacuation also reflects invasive disease. In contrast, enlargement or persistence of theca-lutein cysts is not a reliable marker of malignant conversion and often regresses independently of disease status [Braga et al., 2019, PMID 30815369; Montz et al., 1988, PMID 2455880].