Oc would be the answer to this question
Answer:
B
Explanation:
Chemistry starts with the atom as this is the building block of all chemistry.
The cell, nucleus, and enzyme are all part of biology and not chemistry (at this level at least)
I think its called the <span>doldrums. I had a friend who lived in Africa on the equator and i remember her mentioning this (this was also in 2007, so dont quote me here lol)
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B. One
because an independent variable is something you change. So in a scientific experiment you only change one thing. If you happen to change more than one thing then the test becomes unfair therefore you should repeat and make sure that only one thing is changed this time.