In premature births, one of the dangers that must be overcome is the difficulty in inflating the baby's lungs, because the surfactant has not yet reached an adequate level. In order to breathe, the infant must expand its lungs, breaking down the
bonds between fluid molecules that are trying to keep the lungs from expanding.

it has one origin of replication, but it proceeds in two directions - d)

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.

the answer would be   10%