A. The increase shown at point A is caused by the effect of oestrogen on theanterior pituitary.B. Curve B shows changes in progesterone level during menstrual cycle.C. The source of the increase in concentrations indicated at point C and D aregranulosa cells and corpus luteum, respectively.D. Substance E is secreted by follicular cells.E. The cause of the sudden increase shown at point E is positive feedback ofoestrogen on the anterior pituitary and absence of progesterone.