A farmer is interested in the most effective way of growing his crops. He has several plots of land, and conducts an experiment as follows: He assigns each plot of land to one of three types of fertilizer: Green Thumb Fertilizer, FastGro Fertilizer, and SuperDuper Fertilizer. He also believes that the amount of watering might have an effect. So he assigns each plot of land to either "low-quantity" of water or "high-quantity" of water.

a. What is/are the explanatory variable(s) in the study? What are the treatments?

b. Suggest a response variable that the farmer can use for this study. Make sure to give a specific example, and explain how it can be quantified.

c. The reason that the farmer chose to consider both fertilizer and water amount is that he believes there might be a possible interaction between the two variables. Give a specific example of a way in which interaction could occur in the results. Use one to two sentences.