Which statement best describes a human influence on the biogeochemical cycles?

a) increased eutrophication caused by high levels of nitrogen and phosphorous
b) increased nitrates available due to inaccurate methods of denitrification
c) increased global warming due to alternative energy sources
d) increased amount of water that is available to freshwater ecosystems

Cathy hypothesized that corn would not grow in mud. to test this hypothesis, she took corn kernels and placed 5 in mud, 3 in soil, and 2 in water. to her surprise, the kernels in the mud grew faster than the kernels in the soil. what error might have caused these unexpected results? a. wrong hypothesis b. not enough variables c. undefined control d. too many variables