Before the rise of the Mongols in the 13th century, it is now
called central and western Inner Mongolia, particularly the Hetao region,
change back and forth in control between Chinese agriculturalists in the south
and nomadic Mongol of the north. is known through Chinese chronicles and
historians.
I believe the answer is the weight of each tomato.
This is because the weight of each tomato depends on the amount of fertilizer (the independent variable/the thing being changed) added to each plant.