9 .
Choose the correct order for the changes in the uterus wall which occur every month in a fertile woman.
Egg is released, uterus stays thick, lining breaks down, uterus wall thickens
Egg is released, uterus wall thickens, stays thick, lining breaks down
Uterus lining thickens, stays thick, lining breaks down, egg is released
Uterus wall thickens, egg is released, uterus lining stays thick, uterus lining breaks down