Which statement is true for both incomplete and complete digestive systems?
a.
materials enter and exit through the same opening.
b.
digestion begins outside the cells.
c.
the digestive cavity is like a tube.
d.
continuous feeding is possible.

menstruation is a process in which blood and mucous flows out every month through the vagina. this process occurs every month because one egg is released from the ovary every month and at the same time, the uterus (womb) prepares itself to receive the fertilized egg.

explanation:

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what effect does exercise have on the nervous system?

the answer is c.