Those are really wacky answers to choose from. It isn't B.They are usually man made. It's not C. we still need to be careful. It is not D. It is always your responsibility for whatever you do. It shouldn't be A, but that would kind of make sense. I would choose A.
Answer:
Cell
Explanation:
In anatomy, the basic structural unit of the body is the cell. All living organisms have cells, which start as the zygote — the single cell at the beginning of life, after a spermatozoa fertilizes an oocyte. In humans, the body has more than 200 different cell types.
