Answer:
It seems to be a folded filter paper. But the answer could be funnel as well.
It's the rows. They are periods. (1,2,3,4,5,6,7 - the ones without the letters).
Answer:
d.
Explanation:
i was think b at first but that doesnt really explain how it gets to the circulatory system so d because without the the regulation of the heart rate and oxgen rich blood the muscular system can do absolutely nothing