What changes during a controlled experiment? A. A variable B. The results C. The conclusion D. The hypothesis

Option B

Explanation:

The answer is option B or "the results." Wouldn't be option A because a variable depending on the type is tested during a experiment if you change the variable you have a whole other experiment going on, it wouldn't be option D because your hypothesis is a logically guess at the beginning of a experiment of what you think is going to happen and it doesn't change. It wouldn't be option C because the conclusion is at the end of the experiment after you finished testing, recorded the results, and found out if your hypothesis is correct meaning it doesn't change, leaving option B as your answer.

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age range would be the answer

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?