B!
Parasitism is when one organism benefits and harms the organism it is living off of, while the organism it is living off of will only be harmed and does not benefit.
Because if there is a minimal variation of it the normal state of pH, it can cause severe effects in the brain, arteries, the heart, and other organs.
In other words, it can have some serious effects on the body systems that can lead big diseases, like cancer.
B - energy flow from one tropic level to the next