Corpus luteum is the source of secretion of

The extra-embryonic membranes of a mammalian embryo are derived from

During pregnancy,the levels of which hormones are increased?

The given figure shows the human foetus within the uterus with few structures marked as $A, B, C$ and $D$. Which of the following options shows the correct labeling?

Which structure is responsible for the production of the hormone progesterone?

Why are offspring of oviparous animals at a greater risk as compared to offspring of viviparous animals?