Final answer:
In Raul's experiment, the independent variable is the fertilizer and the dependent variable is tomato production.
Step-by-step explanation:
In Raul’s investigation titled “The effect of fertilizer on tomato production”, the independent variable is the fertilizer since it is the variable that is manipulated by the researcher to observe its effects. The dependent variable is tomato production, which is expected to change as a function of the amount of fertilizer used. In this experiment, Raul is testing how different quantities or types of fertilizer (independent variable) affect the yield or weight of tomatoes produced (dependent variable).