The amount of rain falling on the cactus plants.
Answer: Option C
<u>Explanation:</u>
Here, the independent variable is the amount of rain that makes the cactus plant grow taller. Control is treated the same as all the rest of the samples, except that it is not exposed to variables that are influenced.
In most experiments, it is important to perform a trial with the independent variable, at a special locale for comparison with the other trials.
The control group consists of all trials where the independent variable is left in its natural state. These trials provide a basis for comparison and ensure that any changes observed in the height of cactus plant are in fact caused by the amount of rain.
WWII also created demand: The demand from WWII also boosted the economy so it is hard to determine which caused the economic turn around.
New Dealers argue the economy was already improved before the war had any significant impact. Opponents believe the war was the only impact citing the 1937 recession as evidence.
Farmers in the *Southern Colonies* grew several things. *The most popular crop was tobacco.* The Jamestown colonists had grown tobacco originally, and tobacco farms sprung up all over Virginia and North Carolina. The two southernmost states (South Carolina and Georgia) also grew indigo and rice.