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!
The answer is C. plants pull in CO2 and release oxygen
The handling and movement of controlled substances is Regulated by the DEA (Drug enforcement administration)
One of the main task of the drug enforcement administration is to combating drug smuggling and use within the United states. Hope this helps
