contestada

21. Variables that can change or alter the testing system:
A. can happen by chance only.
B. can happen by chance or by human activity.
C. can happen as a result of causes that are impossible to determine.
D. can happen by human activity only.

Respuesta :

dumbgirl4546

Answer:

I believe the answer is D. can only happen by human activity only

Explanation:

If it is wrong im sorry, I did my best

Q&A Education