In a human female, the reproductive phase starts on the onset of puberty and ceases around middle age of the female. Study the graph given below regarding menstrual cycle and answer the questions that follow :
[Graph of Menstrual Cycle]
(a) Name the hormones and their source organ, which are responsible for menstrual cycle at puberty.
(b) For successful pregnancy, at what phase of the menstrual cycle an early embryo (upto 3 blastomeres) should be Implanted in the Uterus (IUT) of a human female who has opted for Assisted Reproductive Technology (ART)? Support your answer with a reason.
(c) Name the hormone and its source organ responsible for the events occurring during proliferative phase of menstrual cycle. Explain the event.
**OR**
(c) In a normal human female, why does menstruation only occurs if the released ovum is not fertilised ? Explain.