The diagram illustrates a human menstrual cycle. What do X, Y and Z represent?
- AX: the lining of the uterus is breaking down; Y: an ovary releases an egg; Z: a thick uterus lining is maintained
- BX: the lining of the uterus is breaking down; Y: a thick uterus lining is maintained; Z: an ovary releases an egg
- CX: a thick uterus lining is maintained; Y: an ovary releases an egg; Z: the lining of the uterus is breaking down
- DX: a thick uterus lining is maintained; Y: the lining of the uterus is breaking down; Z: an ovary releases an egg