I would say something that makes you use the spinal cord the most (if you catch my drift)...
Hi ^-^
The correct answer is: D. contaminated objects
Hope this helps, and please mark as brainliest!
Use this link:
https://www.khanacademy.org/math/algebra-home/alg-basic-eq-ineq/alg-old-school-equations/v/averages
