The concentrations of LH and oestrogen are monitored over part of a menstrual cycle. On which day does ovulation occur?
- AMarch 25th; LH $= 10$ (arbitrary units); oestrogen $= 30$ (arbitrary units)
- BMarch 28th; LH $= 12$ (arbitrary units); oestrogen $= 135$ (arbitrary units)
- CMarch 31st; LH $= 120$ (arbitrary units); oestrogen $= 130$ (arbitrary units)
- DApril 3rd; LH $= 20$ (arbitrary units); oestrogen $= 25$ (arbitrary units)