Really good question, and really HY.
If it's invasive mole, chorionic villi are present. If the answer is chorio, chorionic villi are NOT present. That's what the USMLE wants for it. If we're dealing with tissue that is pure chorio in real life, villi aren't part of the histology. USMLE wants you to know chorio is a cancer of placental tissue (syncytiotrophoblast; I know you know that, but it's on the NBME/USMLE, so just reiterating).
And then just use your judgement apart from that, e.g., high b-hCG levels and pulmonary metastases for chorio, etc.