Answer:
What Keene High school students are you reading about? And what scientist are you talking about? If you had given more information I would have helped. Anyways, just look at what it says in the book that the scientist did, and what the Keene high school students did. And see what they both have in common.
The answer is C because the load shouldnt be greater than the effort, it isnt usually, but my best answer to you would be C
Trial and Error
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Answer:
leukocyte
Explanation:
leukocyte is the organelle missing in the red blood cell.