You are right it’s D
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<span>The scientist who melted glass to simulate a microscope was Robert Hooke, in 1660. He was an English physicist, and he looked at insects and handheld objects. He named the cell for the cell of a monk, because to him it appeared to be a self-contained room.</span>
D, A
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Answer:
See the answer below
Explanation:
Person X is feeling a burning sensation in several muscles<u> because of the accumulation of lactic acid due to inadequate oxygen in their system.</u> When oxygen becomes inadequate during exercises, anaerobic respiration takes place to augment the oxygen shortage and this leads to the production of lactic acid which accumulates up in the muscles and gives a burning sensation.

Person Y does not feel any burning sensation in their muscles <u>because oxygen is adequate in their system and they do not need to respire anaerobically.</u> <em>Person X exercise regime must have been more rigorous than that of person Y.</em>
Answer:
Why the red blood cell disc in shape is because that is how blood cells carries oxygen around. This is why blood type is important, and how people with a blood type of AB negative is so rare, this is because the AB negative blood cells doesn't have the shape to carry the oxygen needed for the body.
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