Hey There!
Here is your answer:
Your answer is that a experiments should be controlled because the experiment could go out of control which could harm or hurt someone.
Also the definition of a controlled experiment is a part of the experiment that's not touched.
Ex: Water is your controlled experiment that's because our not doing anything to the water.
If you need anymore help just ask me!
Hope this helps!
Answer:
Your answer is B.
Explanation:
Since elements can't exactly "die", the element rather breaks down in the soil below it, and is used again upon the next plant or animal.
Hope I helped :)
