Answer:
An experimental group, also known as a treatment group, receives the treatment whose effect researchers wish to study, whereas a control group does not. They should be identical in all other ways.
That's a hard one but I would go with A unwanted transpitation. Hope that helped :)
Yy.yy is your answer ^-^
Hope am right. Good Luck!
B. plastic , the recycling of plastic would conserve fossil fuels