Students want to determine how vegetation affects soll erosion. They collect four soil samples of equal starting mass with different types of vegetative cover, as seen in the table below. Each sample is placed In a three-sided plastic dish that can drain into a beaker and is exposed to the same amount of consistent, steady rainfall for ten minutes. The water and soil runoff are collected in the beaker and separated.
The average values for each sample are provided below.
Soil Type
Initial Mass Final Mass Average Percent Change in Mass of Soil
Soil with no grass
100g
698
31%
Soil with newly sprouted grass 100g
92g
Soil with mature grass
100g
94g
Soil with dead grass
100g
868
8%
6%
14%
Which of the following is the control group for this experiment?
А
Soil with no grass
B
Soil with newly sprouted grass
С
Soil with mature grass
D
Soil with dead grass