I believe the answer is either A or D. However, I think D sounds the most fitting but like i said, it could be either one. :)
It would be perennial grasses and legumes. :)
Answer: titration curve
Explanation:
A titration curve is a graphical representation of the pH of a solution during a titration. The figure below shows two different examples of a strong acid-strong base titration curve. On the left is a titration in which the base is added to the acid and so the pH progresses from low to high.