What are fish-eating marine mammals that have sleek, short bodies and wide flippers for swimming?
a. pelicans
b. penguins
c. sea turtles
d. seals

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

allowed for the prediction of the properties of missing elements.