Missing hormone identification requires graph analysis

Steps:

• Recall standard menstrual cycle graph: FSH and LH peak mid-cycle for ovulation; oestrogen rises before ovulation and falls after; progesterone rises post-ovulation to maintain pregnancy.
• Examine graph labels: Identify peaks and troughs matching FSH (follicular rise), LH (surge), and progesterone (luteal phase elevation).
• Note absence: No curve showing steady pre-ovulatory rise followed by post-ovulatory drop.
• Conclude missing hormone based on unmatched pattern.

Not enough information: Graph not provided, so cannot confirm which hormone is absent.

Final answer: Not enough information.