Final answer:
In the described experiment, the independent variable is the spraying of the orchard with the chemical, as it's being manipulated to observe its effects on the dependent variable, which is the apple yield.
Step-by-step explanation:
In the context of the experiment described, the independent variable (IV) is the factor being manipulated by the researcher to observe its effect on the outcome. In this case, the independent variable is C) The spraying of the orchard with the chemical, as this is the condition being changed to observe its effect on apple yield, which is the dependent variable (DV). It's important to note that the dependent variable is the one affected by changes in the independent variable, such as the number of grapes harvested or the apple yield.
Factors like a. the amount of water, b. the amount of plant food, c. the amount of soil, d. the amount of sunshine, and e. the type of soil should be controlled, as they might also affect the dependent variable. The control experiment, in this scenario, would be D) The second orchard not receiving the chemical. This helps provide a baseline to compare the results of the chemical's effects.