Answer:
A
Explanation:
I know this because I just took the test and got it right.
To test the effectiveness...
A. This variable should be controlled (the same in both groups).
B. The new chemical is what is being added to the experimental group.
C. This is the control group to which the treated couch should be compared.
D. This is the experimental group to which data should be taken.
Final answer: D
I think it’s the first one - a , but I could be wrong
Cell is the structure used