Answer:
The best answer to the question: Which of the following is the independent (manipulated) variable in the experiment, would be: The chemical.
Step-by-step explanation:
The reason is that all other variables in the experiment remain the same and are unchanging. The point of the experiment is to see what the effects of a specific chemical, on apple yield, is. To achieve this, the scientist has two orchards, each planted with apple trees and both are expected to produce apples. However, the scientist wants to see how the chemical will affect the total yield. So, the one variable that he manipulates on the experiment, is the chemical itself, spraying one orchard with it, and the other leaving it chemical-free. In the end, the results are counted and a conclusion in reached.