A

In a premenopausal woman, a unilocular simple ovarian cyst ≤ 5–6 cm is very likely functional and usually resolves spontaneously; guidelines therefore recommend expectant management with a repeat ultrasound in 6–12 weeks rather than immediate testing or surgery [Alcázar 2005, PMID 16024535; Gerber 1997, PMID 9175670].