A family would like to build a linear regression equation to predict the amount of grain harvested per acre of land on their farm. They subdivide their land into several
smaller plots of land for testing and would like to select an explanatory variable they can control. Which of the following is an appropriate explanatory variable that the
family could use to create a linear regression equation?
A. The total amount of rainfall recorded at their farm
B. The type of crop planted in the plot the previous year
C. The average daily temperature at their farm
D. The variety of grain planted in the plot
E. The amount of fertilizer applied to each plot of land