Astudent compared the chemical composition of soil in a certain area with the bedrock beneath it. she found that the chemical compositions were different. which statement would best explain the difference in chemical composition? a. the soil layers were mature because a large amount of time had passed. b. the soil's rock particles were brought from a different location by erosion. c. the area's water washed iron oxide from the a horizon to the d horizon. d. the area's rain and extreme temperatures caused the soil to develop.