Scientists are interested in how the severity of acid deposition affects the soil of the red spruce forests. They design a laboratory experiment in which rainwater of different pH values is used to water soil samples taken from red spruce forests. The soil samples are the same size and contain the same ratios of sand, silt, and clay. The same amount of water is sprayed on the soil samples every day for a week. Through the experiment, the scientists measured the concentration of toxic forms of aluminum in the soil samples. Identify the likely scientific question being investigated in the experiment.
A. How does the amount of aluminum in the soil affect the pH of the rainwater?
B. How does the pH of rainwater affect the concentration of aluminum in the soil samples?
C. How does the composition of the soil affect the pH of the rainwater?
D. How does the number of days watered affect the concentration of aluminum in the soil samples?